Mammalian phenotypes are influenced by genetics and environment. These two factors rarely operate in isolation, but rather the environment modulates the effects of the underlying genetics. Understanding the molecular basis of such gene-environment interactions is therefore crucial for elucidating the origins of mammalian phenotypes. Within this context, the Rakyan lab is particularly interested in ‘epialleles' – loci at which the epigenetic state varies as a result of stochastic, genetic and/or environmental influences. We pursue several complementary lines of investigation that integrate molecular genomics, computational biology, mouse models, and human cohorts to understand the role of epialleles in complex phenotypes and diseases in mammals.