This review has attempted to provide an overview of the study of gene-environment interaction, starting with early animal studies documenting gene-environment interaction, to demonstrations of similar effects in family, adoption, and twin studies. Advances in twin modeling and the relative ease with which gene-environment interaction can now be modeled has led to a significant increase in the number of twin studies documenting changing importance of genetic influence across environmental contexts. There is now widespread documentation of gene-environment interaction effects across many clinical disorders (Thapar et al. 2007). These findings have led to more integrated etiological models of the development of clinical outcomes. Further, since it is now relatively straightforward and inexpensive to collect DNA and conduct genotyping, there has been a surge of studies testing for gene-environment interaction with specific candidate genes. Psychologists have embraced the incorporation of genetic components into their studies, and geneticists who focus on gene finding are now paying attention to the environment in an unprecedented way. However, now that the initial excitement surrounding gene-environment interaction has begun to wear off, a number of challenges involved
