Rapidly occurring advancements in molecular genetics, such as recent developments in epigenetics, are challenging traditional genetics as it is taught at schools. For example, the adoption of epigenetics--which provides molecular mechanisms for the environment to directly alter phenotypic variation--would mean that pivotal tenets in genetics instruction, such as the central dogma, will require revision. Despite the important implications of epigenetic mechanisms in human health and biological evolution, it is seldom considered at secondary school. The aim of this research was to evaluate the possibility of introducing epigenetics to secondary school students, to foresee the conceptual barriers that might arise and, accordingly, to give some clues which might guide instruction. A short introductory lecture on epigenetics, followed by an open-ended question based in a real case showed that more than half of the students (424 students in 12 schools) were able to understand that environmental factors influence differential gene expression, and over 25% of the students at grade 12 mentioned also some epigenetic molecular mechanisms. However, the students held some conceptual barriers likely hindering comprehension of epigenetics: lack of basic genetic knowledge, genetic determinism, and misunderstanding of the process of adaptation to the environment. The results of this research suggest that it is feasible to introduce epigenetics in secondary school curriculum: at lower levels, special attention should be paid to avoid inducing misconceptions that can work as conceptual barriers to complex genetic concepts exceeding linear determinism; the explicit teaching of technical details might better be addressed at later, post-obligatory levels.