It is important to note there has been increasing attention to the topic of gene-environment interaction from geneticists (Engelman et al. 2009). This likely reflects, in part, frustration and difficulty with identifying genes that impact complex psychiatric outcomes. Several hypotheses have been put forth as possible explanations for the failure to robustly detect genes involved in psychiatric outcomes, including a genetic model involving far more genes, each of very small effect, than was previously recognized, and failure to pay adequate attention to rare variants, copy number variants, and gene-environment interaction (Manolio et al. 2009). Accordingly, gene-environment interaction is being discussed far more in the area of gene finding than in years past; however, these discussions often involve atheoretical approaches and center on methods to adequately detect gene-environment interaction in the presence of extensive multiple testing (Gauderman 2002, Gauderman et al. 2010). The papers by Risch et al. (2009) and Caspi et al. (2010) on the interaction between 5-HTT, life stress, and depression highlight the conceptual, theoretical, and practical differences that continue to exist between the fields of genetics and psychology surrounding the identification of gene-environment interaction effects.
