In the past decade, there has been significant interest in identifying the complex and interacting pathways through which genetic predisposition and environmental factors are associated with complex behavioral disorders (Moffitt et al. 2006; Rutter et al. 2006). Alcohol dependence and drinking behaviors have been identified as a particularly rich case for examining gene–environment interactions (Bearman and Brückner 2002; Guo 2006). Problem drinking is linked to gene expression through multiple pathophysiological systems, but is also driven by social influences like socioeconomic status, family structure, stressful conditions, and socialization (e.g., Singer and Ryff 2001). As a result, the effects of genetic factors are likely to vary substantially depending on numerous environmental contingencies. For example, a genetic effect may be strong and robust in the absence of social controls (e.g., low parental monitoring), but weak or nonexistent when controls are present (Dick et al. 2009). A lack of attention to GxE in this case is problematic since it would likely lead to underestimation of the strength of both genetic and environmental influences, potentially impeding the researcher’s ability to detect statistically significant effects (Heath and Nelson 2002).
