Teaching genetics courses is dominated by a tradition focusing on Mendelian genetics and the central dogma, which can be described as a selective teaching tradition. This theoretical framework refers to a teaching tradition that gives priority to specific content and teaching strategies based on earlier experiences accepted within the community of teachers. This approach is problematic because Mendelian genetics and the central dogma promote a genetically deterministic understanding, leading students to believe that genes alone determine human characteristics. However, this view is increasingly challenged by the emerging field of epigenetics, which emphasises the role of environmental factors in influencing characteristics. Despite this, epigenetics is not yet included in the genetics curriculum in many countries. This study aimed to investigate whether introducing epigenetics to teachers would encourage them to challenge the selective teaching tradition of Mendelian genetics and the central dogma. To support teachers in integrating epigenetics into teaching genetics courses, we therefore developed a professional development programme covering different aspects of epigenetics and genetics education. Data from group discussions and individual reflections were analysed using thematic analyses, resulting in three key themes: keeping the tradition, mixing and adding to the tradition, and changing the tradition. Most teaching strategies fell into keeping the tradition, showing that, despite the development programme, it seemed difficult for the teachers to diverge from the selective teaching tradition. However, the latter two themes suggest that there could be opportunities for incorporating epigenetics into genetics education. This study discusses these opportunities, suggesting how selective teaching traditions might be challenged.