Teaching genetics courses within biology education leans on a teaching tradition based on Mendelian genetics and the central dogma (Gericke & Smith, 2014; Donovan et al., 2020; Dougherty et al., 2011; Johnston, 2023; Radick, 2023). The central dogma describes the flow of genetic information from DNA to RNA to proteins within a biological system, asserting that information cannot be transferred in the opposite direction. The term was coined and first published by Francis Crick in 1958 (Crick, 1958). This teaching tradition, we argue, has evolved into a selective teaching tradition in biology education. It is a theoretical framework within science education that can be understood as a teaching approach prioritising specific content and teaching strategies. This approach is repeated and passed down within teaching communities until it evolves into a canonical teaching tradition, which is taken for granted within that community (Sund, 2016). In this way, the teaching of Mendelian genetics and the central dogma has evolved into a selective tradition within biology secondary education, resisting attempts at change (see reviews of genetic education research by Gericke and Smith (2014), and Stern & Kampourakis, 2017). This implicates an educational problem because Mendelian genetics and the central dogma promote a simplified, causal understanding of the relationship between genes and their associated traits, what in the literature has been denoted as genetic determinism (Condit et al., 2009; Jiménez-Aleixandre, 2014). Moreover, a genetic deterministic view may reinforce undemocratic values connected to sexism and racism (Gericke, 2021; Castéra & Clément, 2014). In this study, we challenge this selective teaching tradition by introducing epigenetics to upper secondary school biology teachers through a professional development programme. The aim of the programme was to investigate whether the introduction of epigenetics would encourage teachers to challenge the selective, deterministic teaching tradition of genetics.

The tradition of teaching Mendelian genetics and the central dogma focuses on genes as the cause of traits (Mendelian genetics) and synthesised proteins (the central dogma) and has been suggested to encourage genetically deterministic thinking among students (Gericke et al., 2017; Stern & Kampourakis, 2017). The use of phrases such as genes for a trait within this teaching tradition gives an impression of a straightforward connection between genes and an individual’s characteristics, which is a rare explanatory model, existing only in a few special cases (Boerwinkel et al., 2017; Kampourakis, 2017). A more contemporary view of genetics recognises complexity as the norm, where multifactorial genetics is central. In most cases, multiple genes and other biological and environmental factors, both within and outside the cell and the organism, interact when genes are expressed (Taylor & Lewontin, 2021). Research suggests that the central dogma should be complemented by findings from the emerging field of genetics, namely epigenetics, which shows that genes and their environment are in constant interaction within cells (Gilbert & Epel, 2009). This is the conceptual knowledge that school biology should promote (Gericke & Mc Ewen, 2023). So far, epigenetics has not been included in the school biology curriculum in Sweden, and the situation is the same in Spain (Zudaire & Fraile, 2021). Although not explicitly mentioning the term “epigenetics”, the Next Generation Science Standards (NGSS) in the US includes in its core ideas that ‘the variation and distribution of traits observed depend on both genetic and environmental factors’ (NGSS, Core idea LS3.B, Variation of Traits N.D.). To highlight the importance of these standards, the New York State P-12 Science Learning Standards, used by the largest public school system in the US, use these standards (New York State P-12 Science Learning Standards N.D.). These examples from a US context show that multifactorial genetics and the influence of environmental factors are beginning to be recognised in curricula as important content. However, this is done without recognising epigenetics as an overarching concept, despite its central importance in genetics education. In contrast, an example where epigenetics is mentioned as a concept can be found in the work of Alonso and Palomares (2021). These authors propose a set of activities, structured into three units, to support students’ learning of the genetic code, genetic variation and epigenetic regulation.

Epigenetics provides mechanistic explanations for how the relationship between nature and nurture becomes concrete and understandable. It shows how genes can be activated or deactivated by environmental factors at the molecular level. Hence, epigenetics serves as an explanatory model for connecting nature and nurture, challenging the canonical teaching tradition based on Mendelian genetics (Gericke, 2021). Stetsenko (2018) declares that biological determinism is dispelled by epigenetics and that no individual’s infinite potential can be predetermined by hereditary disposition alone; potential also depends on the environmental conditions an individual encounters. The same author highlights the importance of understanding the significance of epigenetics from a teaching perspective, emphasising its potential to disrupt inequality and counteract discrimination and marginalisation (Stetsenko, 2017, 2018).

The rationale for this study was to make teachers’ views on including epigenetics in the genetics curriculum more visible in order to understand possible difficulties. Thus, we implemented a teacher professional development programme, aimed at introducing recent scientific knowledge of epigenetics as a core component of the secondary biology curriculum, thereby challenging the traditional focus on Mendelian genetics and the central dogma. The study investigates, against the backdrop of the professional development programme, whether and how the inclusion of epigenetics encourages teachers to challenge traditional teaching genetics courses. We report and comment on what we interpret as teachers’ adherence to a selective teaching tradition rooted in genetic determinism, as well as potential opportunities for changing this tradition. We do this by discussing the possibilities and hindrances that emerged during group discussions and individual reflections collected throughout the professional development programme. The following research question guided the study: In what ways did the teachers reflect on how to include epigenetics within their existing genetics teaching practices?

2.1 Selective Teaching Traditions

A selective teaching tradition can be understood as a way of teaching, including specific content and teaching strategies, which are repeated and passed on within communities of teachers until they evolve into a canonical teaching tradition that is taken for granted within the community. The concept of selective traditions was coined by Williams in 1973 (for a review, see Williams, 2014) to describe how a dominant culture, such as professional groups, incorporates new elements and impulses from the outside without disrupting the status quo of that culture. According to Williams (Williams, 2014, p. 136): ‘the true level of theory and at the level of the history of various practices, there is a process, which I call the selective tradition: that which, within the terms of an effective dominant culture, is always passed off as “the tradition”, “the significant past”’. In such a tradition ‘selectivity is the point; the way in which from a whole possible area of past and present, certain meanings and practices are chosen for emphasis, certain other meanings and practices are neglected and excluded’ (Williams, 2014, p. 136). The cultural theory of selective traditions has since been adopted and used in educational research as a theoretical lens for investigating how communities of teachers build selective teaching traditions that are resistant to change (e.g. Lunde et al., 2020; Gyllenpalm et al., 2010).

Sund (2016) discerns selective traditions in science teaching as follows: ‘if a group of teachers argue and act in similar ways in similar situations, they can be described as working in a similar collective habit’ (p. 387). Lundqvist and Sund (2018) elaborate on this, describing teachers not as isolated individuals, but as belonging to institutionalised systems. These systems can be understood as being created on the basis of contextual situations experienced by earlier generations of teachers, with individual teachers developing their own personal habits in relation to them. In this way, a selective teaching tradition, once accepted within the teacher community, can become strong and resistant to change. It becomes a selective tradition because the teachers in the community select content and teaching strategies that uphold the tradition, often resisting attempts to change it (Sund & Gericke, 2021). For example, Gyllenpalm et al. (2010) showed that when secondary science teachers were introduced to inquiry-oriented teaching approaches, they explained their existing practical work as inquiry, thus expressing resistance to changing their teaching. Consequently, the theoretical lens of selective teaching traditions provides a suitable framework for studying how teachers reason about including the new topic of epigenetics into their existing teaching traditions, influenced by genetic determinism. An existing selective teaching tradition may act as a filter, meaning that teachers, more or less unconsciously, reformulate and adapt new ideas to fit existing ones. This can result in prevailing assumptions not being challenged when new content or teaching ideas are introduced during professional development activities (Sund, 2016).

Based on extensive research on the biology curriculum, textbooks, and biology and chemistry teachers’ beliefs and teaching practices in genetics education presented below, we argue that a selective teaching tradition has evolved in genetics education, based on Mendelian genetics and the central dogma. In the following sections, we will provide an overview of the research that strengthens this argument.

2.2 Existing Teaching Traditions in Teaching Genetics Courses

Teaching genetics courses within the biology curriculum has often relied on a teaching tradition based on Mendelian and classical genetics, as outlined in two previous reviews of genetics education literature (Gericke & Smith, 2014; Stern & Kampourakis, 2017). For example, previous studies have shown that much of the genetics content presented in secondary school textbooks in Sweden largely relies on out-of-date explanatory models from classical and Mendelian genetics (Gericke & Hagberg, 2010a, b). These simplified explanatory models promote a causal and genetically deterministic understanding of genetics and biology, in which genes are described as the cause of a specific trait or behaviour (Gericke & Smith, 2014). Moreover, it seems that this deterministic way of portraying genetics has evolved into a universal teaching tradition in many countries, which is referred to here as the theoretical framework of selective teaching traditions. It has been shown that genetically deterministic explanatory models dominate biology textbooks in Australia, Brazil, England, Sweden and the US (Gericke et al., 2014), as well as in Finland (Aivelo & Uitto, 2015) and France (Clément & Castéra, 2013). Moreover, a Swedish study found that chemistry textbooks build on a tradition of reproducing the central dogma (Wahlberg & Gericke, 2018), which, although molecular, remains a genetically deterministic explanatory model in which traits are equated with proteins. According to the central dogma, the main function of genetic material is to control the synthesis of proteins (as described by Šustar, 2007). Today, we know that protein synthesis is far more complex than suggested by this simplified original model; nonetheless, the central dogma is still canonically reproduced in school biology and chemistry (Wahlberg & Gericke, 2018; Reinagel & Speth, 2016).

From previous research on the biology curriculum, as outlined below, we can identify a strong emphasis on a teaching tradition focused on Mendelian and classical genetics, as well as the central dogma, which promotes genetically deterministic ideas. In a study including in-service and pre-service biology teachers from 23 countries, Castéra and Clément (2014) found that teachers from many countries held genetically deterministic conceptions. Donovan and colleagues (2020, 2021) have recently denoted this focus in teaching genetics courses as ‘basic genomics literacy’, which they define as ‘knowing how meiosis, sexual reproduction, and homologous recombination generate genetic diversity, and how the structure of DNA encodes information needed for protein synthesis’ (Donovan et al., 2021, p. 1481). Furthermore, it was concluded that ‘these knowledges constitute the basis of most genetics curricula’. From this review, we can infer that teachers are constantly encountering a teaching tradition that focuses on ‘basic genomics literacy’. Additionally, we can deduce that it is highly likely teachers normally teach according to this tradition.

Empirical studies investigating how biology teachers enact the genetics curriculum are few, but they point to the existence of the same teaching tradition. In a case study, Aivelo and Uitto (2019) identified three different emphases among teachers in secondary genetics education: structural, hereditary and developmental. Teachers who used a structural emphasis considered gene function as the central issue, while those holding a heredity perspective focused on the continuity of DNA through intergenerational inheritance. Both groups avoided addressing complex traits and human genetics; however, teachers in the third group, who emphasised development, did address these topics. Hence, a teaching tradition focusing on ‘basic genomic literacy’ was commonly found in this study. The same authors also found that secondary students, who were taught with an emphasis on heredity and Mendelian genetics, tended to hold stronger beliefs in genetic determinism than students exposed to other kinds of teaching emphases (Aivelo & Uitto, 2021). Moreover, in-depth case studies of secondary biology teachers’ discussions in the classroom while teaching genetics have revealed a focus on Mendelian genetics and the central dogma, promoting genetic deterministic conceptions, rather than complex multifactorial genetics (Thörne et al., 2013; Thörne & Gericke, 2014).

The tradition of starting teaching genetics courses with Mendelian genetics and the central dogma has been suggested to consolidate genetic deterministic thinking and could, therefore, be considered an educational problem in biology education (Gericke & Smith, 2014; Gericke & Hagberg, 2007; Donovan et al., 2020; Dougherty, 2009). Mendelian genetics, which discusses ‘genes for’ a trait, gives the deterministic impression that there is a straightforward connection between genes and an individual’s characteristics. However, recent genetics research does not support this view, except in special cases, for instance, human blood groups (Storry, 2003). Hence, Mendelian genetics is a rare special case, not in line with the contemporary understanding of genetics, where genes are seen as part of a biochemical system that constantly interacts with its environment. A more updated genetic literacy would address the complex relationship between genetic and phenotypic variation within populations (Boerwinkel et al., 2017). Donovan et al. (2020) have referred to this as ‘standard genomics literacy’, which is grounded in the concepts of population theory and multifactorial genetics. To further strengthen this view, results from previous studies have shown that secondary students have difficulties in discerning more complex genetic concepts, such as multifactorial genetics, when these are embedded in a teaching tradition dominated by ‘basic genomics literacy’ (Gericke et al., 2013).

To conclude, genetics education in general, and secondary genetics education in particular, is dominated by a teaching tradition that canonically reproduces Mendelian and classical genetics, along with the central dogma. As a result, a selective teaching tradition focusing on content that reinforces genetic deterministic views seems to have evolved. This tradition is problematic because it is not up to date with a contemporary scientific view of genetics, reproducing a simplified understanding of genetics, that is, genetic determinism, among students.

2.3 Epigenetics in the Biology Curriculum

Epigenetics, one of the most prominent emerging areas in biology, has changed the prerequisites for a range of disciplines relying on biological knowledge. Epigenetics influences the very heart of cellular processes, as its principal function is to steer which genes are active and which remain silent. The prefix ‘epi’ means over/above, referring to processes that act above the nucleotide sequence of DNA, thus forming epigenetic patterns. These patterns are more or less stable, sometimes reversible, sometimes stable over a whole lifespan when, for example, deciding the fate of cells during cell differentiation. Due to the big impact of epigenetics, some researchers talk about a paradigm shift, pointing to the power of epigenetics manifested during different situations (Gilbert & Epel, 2009). Epigenetics is part of a molecular toolkit that can transmit signals from the environment to the genes. The importance of this is that signals from the environment can influence which genes are active and which remain silent, an information direction that goes against the one dictated by the central dogma. This insight is crucial and one of the main consequences of epigenetics.

Epigenetics has been suggested as a way to update the biology curriculum, moving away from Mendelian genetics and a teaching tradition based on basic genomics literacy. Dougherty (2009) emphasised the importance of epigenetics and suggested that the conceptual idea of complex traits being epigenetically influenced by the environment should be one of the core ideas introduced in the genetics curriculum. The same author called for ‘inverting the curriculum’, beginning with the presentation of common multifactorial traits, instead of using simple monogenic Mendelian traits, to address common genetic deterministic misconceptions. The same approach was also used in an intervention study by Jamieson and Radick (2017). They implemented a genetics course focusing on the role of development for phenotypic variability (historically proposed by Weldon, 1860–1906). In their study, they showed that students who had attended this course expressed less genetic deterministic beliefs compared to those who had attended a traditional Mendelian dominated genetic course. In addition, Redfield (2012) suggested that epigenetics should be included in her suggested syllabus for a twenty-first century genetics course.

Gericke (2021) proposed five contributions from epigenetics, promoting ‘standard genomics literacy’. The main contribution to genetics education, as suggested, was that epigenetics provides an integrated model for gene-environment interaction, explaining how environmental experiences, via epigenetic patterns, become heritable memories within the organism, as described by Gilbert and Epel (2009). These cell memories are dynamic and sometimes reversible (Ramchandani et al., 1999), and they work at time scales between those of cellular gene-environment regulation and evolutionary time scales. In this way, epigenetics contributes to an understanding of genetics with a focus on multifactorial aspects, paving the way for a dynamic understanding of genetics rather than a deterministic one (Gericke, 2021).

Recently, in a Delphi study, an epigenetic literacy framework was proposed based on an expert panel’s view of what aspects of epigenetics ought to be integrated into the biology curriculum (Gericke & Mc Ewen, 2023). Six core ideas were proposed concerning the scientific content (epigenetics as a metaphor, epigenetics connecting nature with nurture, epigenetics as a dynamic process, epigenetic mechanisms, epigenetics and inheritance, and epigenetics and the nature of science). Five core ideas concerning a societal perspective were also proposed (epigenetics in relation to lifestyle, diseases, ethics, policies and forensics). In the study, epigenetics was argued to mitigate genetic deterministic understandings among students. In the same study, the epigenetic literacy framework was linked to the learning progressions of genetics (e.g. Duncan et al., 2009; Todd et al., 2017) as a way to promote genomics literacy and more contemporary perspectives on genetics.

To conclude, epigenetics as part of genetics education has the potential to moderate genetic deterministic approaches, thus making genetics education more aligned with the current research. Therefore, we launched a teacher professional development programme with the purpose of introducing recent scientific knowledge of epigenetics as a core curriculum in secondary biology education, thereby challenging the selective teaching tradition of Mendelian genetics and the central dogma. By analysing the teachers’ discussions during the professional development programme, we investigated if and how the inclusion of epigenetics in genetics education led the teachers to question the selective teaching tradition.

This case study is based on a teacher professional development programme aimed at including epigenetics and thereby questioning the teachers’ existing selective teaching tradition, moving away from a focus on Mendelian genetics and the central dogma.

3.1 The Study Setting

This study is part of a larger research and development project, ‘Epigenetic literacy and the implementation of epigenetics in school biology’. We launched this project to address the need for support in incorporating new, frontline biology into courses in genetics. The overall project encompassed four different phases. In the first phase, consisting of two parts, we identified the content knowledge necessary to teach epigenetics. This was done by conducting a review on epigenetics, framed for biology teachers (Mc Ewen, 2022), and a Delphi-study, developing an epigenetics literacy framework proposing six content themes and five sociocultural contexts to update the biology curriculum adhering to a ‘standard genetic literacy’ perspective (Gericke & Mc Ewen, 2023). Findings from this first phase were included in the second phase, the teacher professional development programme, which is the point of departure of this study. The third phase constituted the development of a specific instructional design framework, constructed in collaboration by the teachers and researchers in this study. The fourth phase is an evaluation of the project. An overall objective of the teacher professional development programme was to support the teachers in their forthcoming elaboration of the instructional design framework.

This study focuses on phase two of the project, where teachers form a community to learn the content of epigenetics and develop it into lesson plans for secondary school biology by participating in lectures, readings, discussions and reflections. The study seeks to describe teachers’views on including epigenetics in the genetics curriculum after participating in this learning community. Understanding teachers’ views is important in order to identify the barriers and opportunities that teachers perceive regarding the inclusion of epigenetics in the genetics curriculum.

3.2 Participants and School Settings

The study took place in Sweden at the upper secondary school level, including grades 10–12. This school level is voluntary, but almost all young people participate. A national curriculum describes the 18 different programmes included at this level of education. The natural science programme prepares students for higher education in science and includes several courses in biology, including genetics. Other programmes also include genetics in a general science course, as a preparation for common knowledge of science, but not at the same depth as the natural science programme. In the biology course (Swedish National Agency for Education, BIOBIO01 N.D.), which specifically addresses genetics, the following content is explicitly addressed:

• Properties and functions of eukaryotes and prokaryotes.
• The structure of gene pools and the laws and mechanisms of heredity, including cell division, DNA replication and mutation.
• Gene expression, protein synthesis, monogenic and polygenic characteristics, heredity and environment.
• Genetic applications, including opportunities, risks and ethical issues.

As can be seen from this quotation from the Swedish national curriculum, the guidance is very general, and nothing is explicitly stated about epigenetics. Content that can be related to epigenetics, such as ‘polygenic characteristics’ and ‘environment’, are contextualised within a Mendelian genetics context, using wording such as ‘heredity’ and ‘law and mechanisms of heredity’. It is important to note that all biology teachers in Sweden are required to teach according to the national curriculum and syllabus. However, at the same time, the general language used in the curriculum provides teachers the freedom to enact the curriculum in different ways, e.g. by including epigenetics.

Ten biology teachers, seven females and three males, volunteered to participate. Nine participants came from one school, hereinafter referred to as the main school, which is the biggest upper secondary school in the region, while the tenth participant came from another school in the neighbourhood. Both schools were situated in a mid-sized city in the south-west of Sweden. The teachers were purposely selected mainly from one school based on the collective participation criterion for designing the programme (Desimone, 2009). The teachers taught genetics at both the advanced and basic levels in the schools. Our idea was to work with teachers who had extensive experience in teaching genetics courses, as genetics is regarded as a complicated field within biology education. Thus, we wanted to discuss genetics and epigenetics with experienced teachers. Eight teachers had worked in schools for 18 years or more, while two had approximately 10 years of experience. The teachers’ average age was 52 years. All teachers had adequate education for their profession, including a relevant and sufficient amount of biology.

3.3 The Teacher Professional Development Programme

The professional development programme was performed during the autumn of 2018. It started with a conference over one and a half days, which introduced the project and the development programme. Thereafter, four meetings were planned, each three weeks apart, after school hours, with each meeting lasting about one and a half hours. Table 1 provides an overview of the teacher professional development programme.

The professional programme was designed based on recommendations from studies on teacher professional development programmes in general (Desimone, 2009; Timperley, 2008, 2011), as well as the science education literature (Schuster & Carlsen, 2009). In this way, we intended to ensure that the development programme would support teachers’ reasoning about incorporating epigenetics into the curriculum. As argued by Timperley (2011), the design was based on what is known, in this case the new knowledge of epigenetics and best practice in genetics education from research; what we know, the teachers’ previous knowledge and beliefs, as revealed from the discussions and previous planning; and new knowledge, which emerged during the discussions when the teachers reflected on their teaching. Timperley (2008) also touched upon the role of external experts in challenging social norms within collegial groups.

As discussed by Schuster and Carlsen (2009), the participation of scientific professionals can be beneficial for participants’ learning. Thus, both scientific and educational experts were engaged in the professional development programme sessions. Since the field of epigenetics was quite new to the teachers, a medical professor and specialist in epigenetics was invited to give a lecture on epigenetics. Inviting scientists is in accordance with the findings of Schuster and Carlsen (2009), who studied scientists’ participation in a teacher professional development course for K-12 science teachers. The authors reported that the teachers valued the interactions with the scientists and stated that ‘a practical recognition [was] that research scientists’ expertise may be with the science, not with figuring out how to teach it to K-12 teachers or within a K-12 setting’ (p. 650). We followed that recommendation and participated ourselves as experts in education, as two of the authors of this study hold PhDs in genetics education, besides the medical professor.

Finally, in the design of the activities, we followed the design criteria identified in the study by Desimone (2009). These criteria are: 1) content focus, 2) active learning, 3) coherence, 4) duration and 5) collective participation. First, Desimone (2009) argued that the 1) content focus of teacher learning might be the most influential feature of effective professional development. The author asserted that activities focusing on subject matter content are linked to students’ learning. In our study, the 1) content focus was expressed through a clear focus on epigenetics. Second, Desimone (2009) emphasised that opportunities for teachers to engage in 2) active learning are also related to the effectiveness of professional development. The author pointed out that active learning could take different forms, e.g. by observing expert teachers followed by interactive feedback and discussions. In our study, we followed this suggestion, and the 2) active learning criterion was expressed in the teachers’ active reflections during group discussions and individual reflections, as well as during the lectures, when we encouraged the teachers to ask questions. Third, Desimone (2009) discussed 3) coherence, the extent to which teacher learning is consistent with teachers’ knowledge and beliefs. In our study, 3) coherence was expressed through the challenging of the teachers’ beliefs about their current teaching practices in relation to the epigenetics content. Thus, we used this criterion in the opposite way, to challenge teachers’ knowledge and beliefs concerning their traditional teaching of genetics. Fourth, Desimone (2009) discussed 4) duration, the required time for effective professional development activities. The author included both the span of time over which the activity is spread, e.g. one day or one semester, and the total hours included, and suggested that research supports activities that are spread over a semester and include at least 20 h. In our study, 4) duration, the professional programme was completed over one semester, and the entire project spanned a full school year (please see the Methods/The Study Setting section for more details on the design of the project). In addition, it included more than 20 h. Fifth, Desimone (2009) underlined that 5) collective participation, the participation of teachers from the same school, grade etc., could be a critical feature for powerful forms of teacher learning. In our study, 5) collective participation was achieved by selecting mainly teachers from the same school in order to establish daily interactions among the participants.

The initial conference served as a social event, where the teachers met to form a group together with the three researchers (i.e. the authors of this study). The different roles of the teachers and the researchers were discussed, resulting in an agreement on mutual expectations. Signed consent forms confirmed this agreement. The remaining mandatory ethical considerations, in accordance with the guidelines from the Swedish Research Council, were reviewed and approved by the ethical committee at the university.

The background and rationale for the project were explained to the participants, with the goal of questioning traditional teaching courses in genetics and developing teaching strategies in line with recent scientific knowledge by including epigenetics. At the conference, three lectures were delivered by the researchers, addressing: 1) epigenetics, 2) genetic determinism, the gene concept and macro–micro problems in teaching genetics courses and 3) learning progressions in genetics. A central question in the project was how epigenetics could be included in today’s teaching genetics courses. To broaden that discussion, the teachers were asked to bring their own plans for teaching genetics to the conference. Finally, the teachers were informed about the types of data that would be collected during the project.

The following four meetings, distributed over two months after the conference, took place at the main school. The meetings started with an introductory lecture on the theme of the meeting, delivered by one of the researchers, lasting about 45 min, followed by group discussions (except for the last meeting). The following themes were discussed: 1) scientific content about epigenetics and the implications of epigenetics for society, with a focus on students’ health through practical examples; 2) epigenetics in relation to the curriculum and teaching theories on how to transform scholarly knowledge into knowledge that is taught and learned in school; 3) genetics education research, constituting a background for discussions on how to introduce epigenetics into genetics education to update the curriculum and 4) aspects of epigenetics that should be included in teaching genetics courses, as suggested by epigenetics experts in a newly performed Delphi-study (Gericke & Mc Ewen, 2023). Each lecture is described in more detail in Online Resource 1.

To provide us with more guidance on the depth and breadth of epigenetics that the development programme ought to contain, we relied on the results from the above-mentioned Delphi-study (Gericke & Mc Ewen, 2023), as the Swedish curricula offered few clues as to what should be included. Most experts recommended that epigenetics should be introduced in lower secondary school (students aged 13–15). They suggested that the content should differ depending on whether epigenetics is included in biology courses at secondary school for students preparing for further biology studies at university, compared to the epigenetics content in general science courses. The latter courses should promote students’ general understanding of epigenetics, with a focus on its implications for the individual and society. Of special interest for the content of the professional development programme from a scientific perspective, the experts recommended that both DNA methylation and chromatin structure (allowing accessibility of gene expression) should be taught to both groups. However, there should be a stronger focus on these topics in courses preparing students for university studies in biology (as with all the suggestions below). The importance of environmental influences on phenotypes through epigenetics mechanisms, the understanding of epigenetics processes as dynamic rather than static, and the role of epigenetics in differentiation were also proposed. Correspondingly, recommendations for the societal perspective included epigenetics and lifestyle, with discussions about lifestyle issues highlighting individuals’ own responsibility for their health, as well as possible connections between epigenetics and diseases (Gericke & Mc Ewen, 2023).

During the group discussions, the teacher group was divided into two or three sub-groups, with one or two of the researchers joining each group. To facilitate a structured discussion, questions related to the theme of each meeting (see Online Resource 2) were distributed at the beginning of each discussion. During the fourth meeting, the teachers discussed how the results from this study could be included in the forthcoming work on a teaching design about epigenetics. Individual reflections were collected no later than one week after each meeting on a shared digital platform. The reflection questions, which can be seen in Online Resource 3, were the same for all individual reflections. The participants were asked to read literature in both English and Swedish between meetings to prepare for the meeting discussions (see Online Resource 4).

3.4 Data Collection and Analyses

Data were collected from two sources: group discussions and individual reflections (see Table 1). There were three group discussions and four individual reflections. The discussions were audio recorded and transcribed verbatim, and lasted approximately 30 min, except for the first meeting, which lasted about 15 min. Not all teachers participated in all group discussions. In the first group discussion, seven teachers participated; in the second discussion, all ten participated; and in the third and last discussion, there were eight participants. Six teachers submitted individual reflections after the first meeting, ten after the second, seven after the third, and six after the last meeting.

The title of this study is “The Challenge of Changing a Genetics Deterministic Teaching Tradition – Teachers’ Views on Including Epigenetics in the Genetics Curriculum”. By the term views, we mean the thoughts, positions and opinions the teachers expressed concerning the inclusion of epigenetics in the genetics curriculum during the group discussions and individual reflections. It should also be noted that a curriculum can be understood as an interactive system of instruction and learning with specific goals, content, strategies, assessment and resources. It is important to note that the discussions and reflections did not address all aspects that constitute a curriculum, but focused more on the specific teaching practices.

The transcribed material from group discussions and the texts from individual reflections were analysed using thematic analysis, according to the six phases described by Braun and Clarke (2006). These phases are shown below in the numbered list, together with explanations of how the analysis was performed. The development or progression of each individual teacher’s reflections was not registered, as the analysis was performed on the transcripts and texts from the whole teacher group. The process was iterative, in the sense that it moved back and forth, collecting new perspectives from earlier steps during the ongoing process. We do not report on how common a theme was in the data; however, we do comment on the frequency of supporting excerpts for the different themes in the results section.

3.4.1 Phase one: Familiarising yourself with your data

The analysis started with a careful examination of all texts to familiarise ourselves with the data, revealing its depth and breadth. The texts were read repeatedly in an active way, searching for meanings and patterns related to how epigenetics could be included in teaching genetics courses, in connection with the research question. During this phase, notes were taken and ideas highlighted for how to code the data. Special sections of the texts were marked for suggestions of initial codes.

3.4.2 Phase two: Generating initial codes

The unit of analysis was determined for meaningful text excerpts, hereinafter called data extracts. These data extracts could range from a single sentence to longer dialogues between the teachers relating to a well-defined aspect of teaching genetics courses. The aim of the coding process was to identify different ways of including epigenetics in teaching courses in genetics and how this would affect their genetics course. The codes were generated inductively, and each identified data extract was assigned an initial code. The coding process was performed systematically and manually, identifying interesting aspects of the data that could form the basis of repeated patterns. To get an overview of the data, the coded data extracts were compiled into an Excel spreadsheet.

3.4.3 Phase three: Searching for themes

In this phase, we considered how the differently coded data extracts could be combined to form potential themes. Thus, after collating all the relevant coded data extracts, these were re-arranged in the Excel diagram. The search for potential themes was inductive and relied on the research question relating to how the teachers reasoned about ways to include epigenetics in relation to their existing teaching practices in teaching genetics courses. Thereafter, within the potential themes, the process was iterated, and sub-themes were inductively suggested within each theme. The further process involved refining the potential themes and sub-themes.

3.4.4 Phase four: Reviewing themes

The potential themes were further analysed in an iterative refining process, which was considered to be the best description of the data. The potential themes cohered together meaningfully when they described a distinct trajectory in the data, that is, how the teachers aimed to incorporate the new material of epigenetics into their teaching genetics courses. The potential themes also revealed identifiable differences that distinguished them from each other. This refining process was repeated for the potential sub-themes.

3.4.5 Phase five: Defining and naming themes

This phase involved the final refinement of the potential themes and sub-themes. It included a check of the relevance of each theme and sub-theme. At this stage, a detailed written analysis of each potential theme and sub-theme was conducted, resulting in a suggestion on how to name the themes and sub-themes.

3.4.6 Phase six: Producing the report

The themes and sub-themes were ultimately analysed, defined and named according to how the teachers reasoned about a possible integration of epigenetics into their teaching genetics courses. This analysis resulted in three themes; furthermore, sub-themes were identified and named within each theme. To provide a richer description of the data, the themes and sub-themes include numerous vivid excerpts that capture the essence of the theme/sub-theme. These excerpts exemplify the teachers’ utterances and are marked Teacher 1 to Teacher 10, [T 1] – [T 10].

After analysing the teacher group discussions and individual reflections, we concluded that there were different strategies on how to handle a possible inclusion of the new content of epigenetics into the teaching genetics courses. The three themes include: keeping the tradition, mixing and adding to the tradition and changing the tradition. Most strategies fell into keeping the tradition, while there were fewer coded excerpts under the other themes, where a process of negotiation for change had started. Citations supporting all three themes are shown below.

4.1 Keeping the Tradition

Despite the professional development programme showing the importance of including epigenetics early in the genetics course, the teachers wanted to keep the traditional approach to teaching genetics courses. The three sub-themes below illustrate the teachers’ arguments for justifying their choices. These arguments can be considered as obstacles to change, highlighting that the teachers followed a selective teaching tradition. In the first sub-theme, the teachers claimed that Mendelian pedigrees were easy for students to understand, and that using these, e.g. by checking each other’s dimples and hairlines, helped create a relaxed feeling in the classroom, constituting a good starting point for teaching genetics. In the second theme, they argued that the central dogma forms the foundation of teaching genetics courses and referred to its crucial role in textbooks and during their own university education. In the third theme, the clarity of Mendelian inheritance patterns, e.g. genes remaining intact through generations, was highlighted as a strong advantage for keeping the tradition. Below, the three sub-themes provide examples of supporting excerpts.

4.1.1 Mendel Starts Teaching Genetics Courses

Mendelian genetics, with its pedigrees, was highly appreciated for a variety of reasons, the first being that ‘it was such a fun introduction to the subject’ [T 2]. The teachers described how they started the genetics course by handing out a paper illustrating different examples of characteristics that were supposed to be decided by dominant genes, e.g. whether you have dimples, can roll your tongue, or the shape of your hairline. The students became engaged in checking their own and their peers’ characteristics, leading to much laughter in the classroom. The situation also included the teachers: ‘You are supposed to walk around and check everyone’s hairline’ [T 8]. Furthermore, Mendelian pedigrees were experienced by the teachers as easy for students to understand.

… the penny drops pretty quickly, though, when they [the students] understand … why there are boys … and girls … That is a very simple way of looking at it, you know, one gene, one trait … I think it wouldn’t make sense to remove them [Mendelian pedigrees]. [T 9]

4.1.2 A Central Place for the Central Dogma

There was a consensus within the teacher group that the central dogma, with its focus on the importance of genes in shaping individuals’ characteristics, holds a central place in teaching genetics courses. All the teachers expressed a preference for sticking to their traditional approach to teaching as a baseline. This view was maintained despite discussions during the programme about starting teaching genetics courses from a perspective where genes and the environment interact to form the phenotype. We argue that the following discussion between three of the teachers exemplifies the view that genes were regarded as the foundation of teaching genetics courses.

[T 5]We teach genetics … which deals with how we inherit things … that is sort of the main content, you know … even though we include environmental influence … also … it’s introduced somehow … now we are working with genetics, and that is about how heredity works … it’s not strange that we have … made that choice to focus more on that.

[T 9]I think it would be really difficult to begin from the other end, to take interaction … we have the environment here … and it contributes and determines … I think that would be a very difficult explanation to start with.

[T 7]… yes, exactly …

[T 9]… the environment is there and directs our genes so that … in the end, there is a kind of expression of this thing that is a mix of the two …

[T 5]… yes …

[T 9]… this is where we feel safe …

Furthermore, the teachers pointed to the central dogma as the predominant perspective in textbooks. ‘The central dogma … it’s there in all textbooks used in schools, you know…’ [T 9]. To further justify their choice of using the central dogma in teaching genetics courses, they referred to their own university education, where the central dogma was the norm.

My biology education … was completed so far back, you know, that classical genetics; that’s what I learned, and, of course, it might happen that I still teach it incorrectly in a way. [T 7]

4.1.3 Mendelian Genetics Discerns Genes as Separate Units

The clarity of Mendelian inheritance patterns was suggested as a distinct advantage in teaching genetics at the secondary level. One example provided to students was that they could regard themselves as a combination of characteristics from both their mothers and fathers. It was also explained that genes are not mixed when transferred from one generation to the next, but continue to exist as separate units, which is easy to follow across generations.

The major benefit of doing this classical thing is that they [the students] can see that it’s about the combination of the mother and the father … [T 1]

… and then they [the genes] are still there, right? They are not mixed … they are separate units … they actually remain in the next generation … there is no mixture … well, not a soup anyway … it can be seen really clearly … after several generations … ok, why have I got my grandfather’s nose … how come … my nose is crooked in that particular way? … Things that are inherited in a direct descending line are clear and obvious, you know … [T 1]

Another advantage of the clarity of Mendelian inheritance was pointed out in the case of students potentially needing genetic counselling in the future. The example is about the risk of inheriting transgenerational diseases.

If, for instance, there is a disease in the family … according to Mendelian … percentages … a twenty-five per cent risk that this particular child will inherit the disease … it’s not entirely … a bad thing to have it [Mendelian genetics] as a basis, I think. [T 1]

4.2 Mixing and Adding to the Tradition

The theme of mixing and adding to the tradition shows that the teachers continued to use the traditional genetic deterministic teaching approach. However, they had begun on a trajectory that opened up space for the inclusion of new content. These openings indicate that, despite their anchorage in traditional methods, the teachers found possibilities to include new content in their teaching genetics courses. We describe these openings in the three sub-themes below, where the first focuses on the mix of Mendelian and molecular genetics, and the other two focus on adding to the tradition. Factors that could facilitate a change in teaching courses in genetics are also highlighted.

4.2.1 Mixing Mendelian and Molecular Genetics

The teachers saw possibilities in using a well-known and traditional context as a foundation and then incorporating new knowledge in place of the existing content. It seems as though this strategy was a gateway for introducing change. Hence, the teachers suggested retaining the context and examples from Mendelian genetics while replacing the content with material from molecular biology. This approach could be interpreted as ‘you take what you have and use it in another context’. To test the idea, the teachers experimented by replacing Mendelian crossing designs of yellow/green and wrinkled/smooth peas with different proteins. They emphasised that the result of gene expression is the formation of proteins, which, through biochemical processes in the organism, result in different characteristics.

We could use a crossing design and show that a certain protein is the result of it and that this protein, in turn, … is part of a complex system that yields certain traits … Instead of yellow peas, we could have protein A or something, and protein B. [T 1]

The following two sub-themes illustrate the teachers’ thoughts on just adding epigenetics into the existing traditional genetics curriculum. In the first sub-theme, they reasoned that if epigenetics were to be included in teaching courses in genetics, it should be introduced only after covering traditional genetics. In the second, they suggested that epigenetics could be presented as an additional model, just added to already existing ones. This means that the teachers did not need to renegotiate what they were familiar with. However, we interpret this strategy as an opening to include epigenetics and a potential factor in changing the traditional teaching style.

4.2.2 Adding the Influence of the Environment after Introducing the Central Dogma

The teachers regarded the central dogma and deterministic thinking as a basic understanding of genetics, to be established before introducing environmental influences. They saw the environment’s contribution to gene expression as something that was added on, rather than an equivalent part to be introduced in parallel to the concept of genes.

It’s hard to begin … first you have to explain … some basics … there is some kind of code and blueprint in DNA, anyway … how these are used … can be determined by the environment. [T 5]

It feels as though we are still stuck in the traditional way, perhaps starting from determinism … To some extent, I still believe in the idea that it may not be entirely wrong to begin with some kind of foundation in the deterministic … doctrine, and then it’s possible to build on that and say, no, it works a bit differently … it’s much more about the environment and its, well, ability to influence things. [T 9]

The teachers also suggested introducing the environment’s influence by initially ‘misleading the students. First, they would explain the central dogma and then, only afterwards, introduce the role of the environment through discussions about the impact of lifestyle choices. The teachers speculated that teaching could start with characteristics determined solely by genetics, e.g. blood groups, before continuing with characteristics where environmental factors plays a role. This is exemplified in the conversation between two of the teachers below.

[T 2]… that we might begin with something that is really … deterministic

[T 7]… yes …

[T 2]… blood types or something like that …

[T 7]… yes …

[T 2]… which actually …

[T 7]… exactly …

[T 2]… is not influenced …

[T 7]… yes …

[T 2]… at all by anything …

[T 7]… no …

[T 2]… nothing else, you know …

[T 7]… no …

[T 2]… and then, maybe, present an example [of how lifestyle matters]

4.2.3 Adding Epigenetics to Other Models

The next example of adding epigenetics into already existing models came from a teacher who placed epigenetics within a broader context. This teacher highlighted the use of models in schools, models which, according to this teacher, could be regarded as ‘fragments of life’. Mendelian genetics and molecular genetics were two such models, not in competition with each other; rather, Mendelian genetics provided certain keys to students’ learning, while molecular biology offered insights more closely related to their everyday life experiences. In this way, epigenetics functioned as a third model, one that, together with other ‘fragments of life’, could help us to get a better understanding of life.

I still find it hard to see why it turns into such a big problem that classical genetics and molecular genetics … are in conflict. I don’t really recognise it myself, but if we make it even clearer than before, namely, that we work with models in school … models that provide fragments, albeit important fragments, which help us understand how life works … and put things into context. We can never understand everything about life and all biological and chemical processes; it’s far too complex … but in school, we select important aspects of science … and create a certain understanding of biology, of chemistry; but remember, it’s never the entire truth … it’s never a complete picture. We give you a few keys … and my take on it is that Mendelian genetics gives me a few keys. I still think that it offers good points, really, that I want to use … Watson and Crick’s DNA model provided me with really important fragments and still … this emphasis on epigenetics adds another layer … of understanding which is good, but it won’t give me the complete picture either. It’s one more fragment that helps me get closer to the truth about, or an understanding of, how we work. [T 10]

4.3 Changing the Tradition

There were incipient considerations within the teacher group to replace Mendelian genetics with a more contemporary approach to teaching genetics. This is reflected in the following two sub-themes, which encompass both tentative ideas and more established, already existing, examples of teaching in the classroom. However, it seemed that some teachers had already begun to highlight the relevance of environmental factors in shaping individual characteristics, that is, conceptual implications of epigenetics, but without explicitly referring to the concept of epigenetics, or to epigenetic mechanisms. The first sub-theme shows how teachers had started to reconsider aspects of their existing teaching approach, possibly preparing to exclude some of the old content and replace it with more up-to-date scientific knowledge. In the second sub-theme, the arguments for including the environment’s influence on individual’s characteristics show that the concept of epigenetics was already there, however, not explicitly expressed. The two sub-themes reveal possibilities and openings for a change in teaching courses in genetics.

4.3.1 Molecular Biology as a Foundation for Epigenetics at the Expense of Mendel

Some discussions centred how much classical Mendelian genetics should be taught in comparison to molecular biology in order to facilitate the implementation of epigenetics. Reflections were made about running both tracks in parallel from the start or giving molecular biology a greater role throughout the whole genetics curriculum. These two excerpts show that some teachers had started a process of negotiation and argued tentatively for a change.

How much ‘basic knowledge’ do they [the students] need to understand epigenetics? Or can these two tracks [classical Mendelian genetics and molecular genetics] be taught in parallel from the beginning? [T 8]

It might be an advantage that the main part of the course content has focused on molecular genetics (DNA, RNA, protein synthesis), which could make it easier to expand the content with more epigenetics. [T 5]

This third excerpt involves a teacher who had progressed further in the process of giving more importance to molecular biology and epigenetics in teaching genetics courses.

I have been ‘forced’ to reflect upon how much of the content in teaching genetics courses should focus on classical/Mendelian genetics versus molecular genetics and also more modern epigenetics. Perhaps I should make much more room for molecular genetics, especially epigenetics? [T 10]

4.3.2 Epigenetics Contributes a New Explanatory Model

During the group discussions, it became obvious that some of the teachers had already established an advanced approach to teaching courses in genetics, including the importance of the environment in shaping individuals’ characteristics. This shows that some teachers were already grounding their teaching in an integrated perspective on nature and nurture, although they did not explicitly address the concept of epigenetics. During the professional development programme, the teachers recognised that their teaching could be further developed by introducing the mechanistic explanation model of epigenetics to support this integrated perspective.

The excerpt below shows one teacher describing her approach to introducing the importance of the environment in shaping individuals’ characteristics. She does so by utilising at least some youths’ presumed interests in bodybuilding, pointing out the need for physical exercise to build muscles. However, she did not explicitly explain the epigenetics mechanisms; rather, she reasoned that epigenetics could be introduced as well. She also suggested finding more examples to highlight the role of epigenetics in supporting an integrated perspective on nature and nurture.

I guess, I often use some kind of an example like this. You have a genetic pre-disposition to build muscle … but if [you] sit in the dark in your basement and never move around or exercise, you won’t build muscle anyway … That connection is quite easy for them to grasp … The environment plays an obvious part … But maybe, we could find more of those [examples]… to bring up epigenetics as well. [T 2]

Another example was that of identical twins, who become more and more diverse over the course of their lives despite identical genes, due to different environmental influences on their bodies. Although this example was pointed out as commonly used, the teachers did not seem to have reflected on it in terms of epigenetic mechanisms.

I think they [the students] find it easy to accept when we talk about twins who … live in two different environments … and turn out quite differently as individuals … they are affected by, well, everything social, sort of everything that people are exposed to … and how people somehow live their lives, and all that, how they are active and what they eat and [how they] exercise. [T 9]

The results of this study show that, despite the teacher professional development programme about epigenetics and its role in updating teaching genetics courses, all the teachers most often expressed a preference for sticking to their traditional teaching methods. We interpret this as evidence that they were working according to a selective tradition (Sund, 2016). However, we also report on openings, which could be of importance for understanding why some teachers were prepared to negotiate changes in their traditional approach to teaching courses in genetics.

Much of the data show that the teachers did not want to change their present approach to teaching genetics courses; instead, they wanted to keep the tradition. The teachers had arguments for keeping the traditional genetic deterministic teaching approach and identified hindrances in initiating a change, as exemplified by the following main arguments. 1) The main content of genetics is about genes and their importance in shaping individuals’ characteristics. The teachers argued that, at least during the start of teaching genetics courses, explaining the interaction between genes and the environment in the formation of the phenotype would be a very difficult task. Given their limited background knowledge, the teachers claimed that it would be too difficult for students to understand the interaction between genes and the environment for the formation of the phenotype at that point. Furthermore, the teachers considered that this idea would depart too far from the trajectory of the main point they are trying to make. 2) Genetics is about inheritance. The teachers reasoned that the use of Mendelian genetics, emphasising genes as separate units, could facilitate the understanding of how characteristics are transferred across generations. Common examples include the inheritance of dimples, the ability to roll one’s tongue, or different hairline shapes. Additionally, by downplaying the view of genes as separate units, students might miss valuable information about the inheritance of genetic diseases, which could be crucial if they need genetic counselling in the future. 3) The teachers argued that starting teaching genetics courses with practical activities focusing on specific human characteristics, e.g. checking hairline shapes, all supposed to be 100% inherited, contributed to an engaged and student-motivated atmosphere in the classroom. They thought that taking away such appreciated moments in education would be a pity.

The above-described arguments and hindrances to change could be challenged. The traditional approach to starting teaching courses in genetics, that is, with Mendelian genetics followed by the central dogma, implies presenting students with a deterministic perspective, where the genes decide the fate of the phenotype (Gericke et al., 2017; Stern & Kampourakis, 2017). This view creates the impression of a straightforward connection between genes and the phenotype, which is, in reality, a rare phenomenon (Boerwinkel et al., 2017; Kampourakis, 2017). Today, a more complex understanding of genetics has emerged, where environmental factors interact with genes to shape an individual’s characteristics (Gilbert & Epel, 2009). Multifactorial genetics, emphasising how several genes can influence a single trait, or how a single gene can affect several characters, could be important factors in focusing on the influence of the environment on gene activity (Gericke & Smith, 2014; Donovan et al., 2020; Stern & Kampourakis, 2017). Dougherty (2009) calls for ‘inverting the curriculum’, beginning with a presentation of common multifactorial traits, instead of using simple Mendelian traits, to address common genetic deterministic misconceptions. This could also be articulated in terms of a ‘basic genomics literacy’ (Donovan et al., 2021), which should be replaced with a ‘developmental, structural and hereditary genomics literacy’, as proposed by Aivelo and Uitto (2019). To sum up, despite a consensus to downplay Mendelian genetics and the central dogma in teaching genetics courses in favour of a more up-to-date and nuanced picture of genetics, the results from this study show that there is some reluctance towards such a development, at least among the upper secondary school teachers participating in this study.

Furthermore, the second argument, which uses examples of assumed genetically determined traits linking genes with specific human characteristics, is problematic. None of these examples have been shown to be inherited to 100% (Sturtevant, 1940; Thibaut et al., 2005; Wiedermann, 1990), implying the involvement of the environment in shaping the phenotype. Some exercises might help students understand how these theoretical arguments could be translated into practice. For example, you will never be a top athlete if you do not exercise, despite inheriting favourable genes from your parents. Another example is about taking care of your body to avoid diseases. More examples will be described in the teaching design on how to implement epigenetics in the genetics course in the third phase of the project. The last argument, where practical activities were thought to contribute to a relaxed atmosphere in the classroom, might be interpreted as the esteemed embodied practical activities being given priority over the content. Other examples with an epigenetics context, also contributing to a relaxed atmosphere, could be developed, but this requires time and effort to elaborate. Why change something that works?

We argue that this reluctance to give up the deterministic view, at least at the start of teaching genetics courses, demonstrates that the teachers were working according to a selective tradition. Signs of working according to a selective teaching tradition that supports a genetic deterministic perspective were also observed in the theme of mixing and adding to the tradition, where existing concepts of Mendelian genetics were suggested for use in new contexts. Mixing pre-existing concepts with new content is described by Lunde et al. (2020), who designed a study to raise lower secondary school teachers’ awareness of, and encourage discussion about, the existence of selective teaching traditions. The study showed that new material was simply incorporated into old structures, without changing the concepts used, thus failing to allow the new material to remake and transform the science education. The same phenomenon was seen in this study, when the teachers discussed modifications that conformed to already pre-existing concepts. However, this way of mixing concepts and models from classical genetics with aspects of molecular genetics, termed hybridisation (Gericke & Hagberg, 2010a, b), might be problematic. Different gene concepts are used interchangeably, which could cause learning difficulties among students (Gericke & Hagberg, 2007). To conclude, the similar collective habit of the teacher group in this study, where the teachers sought to continue traditional teaching of genetics courses only by mixing traditions of classical and molecular genetics, indicates that the teacher group acted according to a selective tradition of teaching genetics courses.

The theme of mixing and adding to the tradition displays an incipient degree of acceptance to negotiate at least some epigenetics into teaching genetics courses. The teachers reasoned that the influence of the environment on shaping individuals’ characteristics was something that could be added to a starting point with Mendelian genetics and the central dogma. The teachers articulated that you first need a foundation, and that foundation is DNA, before the effects of the environment could be introduced. They explained that you have to start with the traditional, and then tell the students that this is not exactly right, and that you also have to consider the environment’s influence on gene expressions. However, as noted above, this is a risky position, as it highlights a few easily inherited patterns and exceptional cases of a direct link between genes and characteristics (e.g. Storry, 2003). This could give students a false impression that all characteristics, not just those exceptional cases, depend on a straight line from genes to characteristics, thereby focusing on a deterministic perspective. One of the main consequences of epigenetics is that, on almost all occasions, the environment and the genetic material together decide which genes are expressed. We interpret the teachers’ reasoning to add something to already well-known traditional education as a compromise: the teachers took a small step towards a more modern epigenetic explanation of how genes are expressed. We conclude that these instances demonstrate an opening for changing traditional teaching of genetics courses.

Thoughts about making more room for molecular genetics (DNA, RNA, protein synthesis and especially epigenetics) at the expense of Mendelian genetics showed that at least some teachers were in the process of changing the tradition. In fact, examples of the connection between genes and the environment were present when discussing the environment’s influence on the phenotype’s characteristics. However, we could not be sure that the teachers were truly thinking about an integration of epigenetics, in the sense that the environment and the genes together decide which genes will be expressed, as opposed to simply adding the influence of the environment to the effects of genes. In the examples the teachers provided, the role of epigenetics connecting genes and the environment in shaping the phenotype was not accentuated by the teachers.

We found that the best examples of what could encourage the teachers to change the tradition occurred when practical implications for the students, coupled with epigenetics mechanisms, were the focus. As epigenetics provides molecular answers to what happens in our bodies during everyday life, it matters which lifestyle choices we make. Physical exercise has been shown to change epigenetic patterns in the body significantly (Hall et al., 2020; Lindholm et al., 2014), as well as food choices (Florean, 2014). This connection between lifestyle and health was also highlighted by an expert panel in a Delphi study, which suggested that epigenetics and lifestyle should be one of five sub-themes, with societal perspectives, included in an epigenetic literacy programme for secondary schools (Gericke & Mc Ewen, 2023). Some teachers had already incorporated these topics into their teaching, without explicitly referring to epigenetics. It seemed that, to reinforce an already interesting topic for the students, a topic relying on epigenetics knowledge could be an accessible way to include epigenetics in genetics education. As the teachers had already identified these topics as interesting and important for the students, they had no hesitation in using these examples. Thus, we conclude that a successful opening for change could be to support teachers in incorporating more practical topics, grounded in epigenetics mechanisms, that are of importance to students’ everyday lives.

We are aware that the responsibility of introducing recent scientific knowledge, such as epigenetics, in school science should not solely be placed on the teachers. The responsibility ought to be shared between teachers and the collaborative creators of standards, curricula, textbooks, national assessments, etc., for example, national committees developing learning progressions and curricula. Indeed, all these stakeholders, together with teachers, jointly form the dominant culture that establishes the selective teaching tradition (Williams, see McGuigan, 2014; Sund, 2016). Therefore, all stakeholders influencing biology education have a collective responsibility to break the selective teaching tradition of genetic determinism. It might actually be difficult for teachers to break away from this teaching tradition, although Swedish teachers have a great deal of freedom to do so when enacting the general stated national curriculum. Despite this, our study has contributed some suggestions for teachers who want to move away from a genetically deterministic teaching tradition. Other studies should investigate the roles of other stakeholders in this endeavour.

Our choice of selecting only experienced teachers for this study could be challenged. Novice teachers have a more recent biology education, possibly including epigenetics, and might thus be more likely to adapt their teaching. However, the most important reason for excluding novice teachers was that the majority of biology teachers in schools could be regarded as experienced. Thus, our decision to select only experienced teachers resulted in findings that are relevant for the majority of biology teachers. While it might be assumed that it is easier for new teachers to change, it is actually more challenging for them to alter an existing and established teaching tradition (Sund, 2016). Due to the significance of such tradition in this case, it is more relevant to focus on experienced teachers, as they usually have a greater influence on the prevailing culture. It should be kept in mind that the sample is very small and the results are not necessarily generalisable. As expected, teacher comments did not come evenly from all teachers; however, we perceived that the more vocal teachers expressed and summarised what the group wanted to deliver.

It could be argued that the presence of researchers during group discussions influenced the teachers not to be entirely open. When deciding how to collect the data, it was considered important for the researchers to join the groups in order to answer questions about epigenetics and research on teaching genetics, as these topics were new to the teachers. We tried to steer the group discussions to be as open as possible, but sometimes one or more teachers, or even the whole group, disagreed with a statement made by us, indicating a somewhat uncomfortable feeling within the group. Their hesitation about omitting traditional teaching of genetics courses when including epigenetics could be regarded as a sign of confidence. However, to strengthen the teachers’ possibilities to have their voices heard in as unaffected a way as possible, they were given the option to submit individual reflections after each meeting. Some reflections questioned different parts of the programme, and we interpreted these as the teachers expressing their honest thoughts and opinions.

As shown above, by introducing epigenetics into a teacher professional development programme, we found openings for challenging the traditional teaching of genetics courses that supports a deterministic perspective. We claim that the same strategy to challenge selective teaching traditions could also be applied to other topics and disciplines. By adding new concepts to already familiar ones from traditional teaching, the teachers took steps towards adopting new perspectives. The use of already implemented practical and interesting examples from students’ everyday lives, e.g. the importance of physical exercise, helped broaden the teachers’ views. Hence, we argue that taking advantage of an already open trajectory towards students’ interests could be a way to introduce new perspectives. These findings could serve as an inspiration for how to challenge selective traditions in other topics and disciplines as well, by introducing a “bridge” between familiar, traditional teaching and the new perspectives.