Models are often used when teaching science. In this paper historical models and students' ideas about genetics are compared. The historical development of the scientific idea of the gene and its function is described and categorized into five historical models of gene function. Differences and similarities between these historical models are made explicit. Internal and external consistency problems between the models are identified and discussed. From the consistency analysis seven epistemological features are identified. The features vary in such ways between the historical models that it is claimed that learning difficulties might be the consequence if these features are not explicitly addressed when teaching genetics. Students' understanding of genetics, as described in science education literature, is then examined. The comparison shows extensive parallelism between students' alternative understanding of genetics and the epistemological features, i.e., the claim is strengthened. It is also argued that, when teaching gene function, the outlined historical models could be useful in a combined nature of science and history of science approach. Our findings also raise the question what to teach in relation to preferred learning outcomes in genetics.