Science education strives to increase interest in science and facilitate active citizenship. Thus, the aspects of personal and societal relevance are increasingly emphasised in science curricula. Still, little is known about how teachers choose content for their teaching, although their choices translate curricula to teaching practice. We explored how teachers choose genetics content and contexts for biology courses on cells, heredity and biotechnology by interviewing ten Finnish upper-secondary school teachers. We studied how the teachers described teaching on three themes in which they have varying freedom afforded by curricula: genetically modified organisms, hereditary disorders, and complex human traits. We analysed interviews with theory-guiding content analysis and found consistent patterns in teachers' perceptions of the themes in genetics teaching and teacher inclinations towards teaching genetics in human context. These patterns, which we call emphasis of content in genetics teaching were Developmental, Structural and Hereditary. Teachers with Developmental emphasis embraced teaching genetics in a human context, while teachers with a Structural emphasis avoided them. In general, teachers justified their choices by national, local school, and personal factors. While teachers mentioned that societal and personal contexts are important, at the same time teachers never framed the main themes in genetics with these contexts.