An enduring question remains in the study of gene-environment interaction: how does the environment “get under the skin”? Stated in another way, what are the biological processes by which exposure to environmental events could affect outcome? Epigenetics is one candidate mechanism. Excellent recent reviews on this topic exist (Meaney 2010, Zhang & Meaney 2010), and I provide a brief overview here. It is important to note, however, that although epigenetics is increasingly discussed in the context of gene-environment interaction, it does not relate directly to gene-environment interaction in the statistical sense, as differentiated previously in this review. That is to say that epi-genetic processes likely tell us something about the biological mechanisms by which the environment can affect gene expression and impact behavior, but they are not informative in terms of distinguishing between additive versus interactive environmental effects.
