Both social environment and genetic factors have long been implicated in alcohol use (Kendler et al., 2008; Zucker, 2006). Recent studies also point to the presence of gene by environment (G × E) interactions, such as specific genetic polymorphisms being associated with increased susceptibility to environmental influences (Belsky and Pluess, 2009). One genetic polymorphism of interest in the alcoholism literature is the number of variable number tandem repeats (VNTR) in the third exon of the DRD4 dopamine receptor gene. The presence of a long DRD4 allele (involving 7+ repeats) decreases dopamine reception efficiency (Asghari et al., 1995) and has been linked with increased craving in response to alcohol cues (McGeary, 2009; Ray et al., 2010), greater alcohol use (Vaughn et al., 2009), and personality correlates of alcohol use such as thrill seeking (Dmitrieva et al., 2011), as well as other types of problem and addictive behaviors such as delinquency (Boutwell and Beaver, 2008) and smoking (Hutchison et al., 2002). This study examines the interaction of DRD4 polymorphism with a key environmental factor in alcohol use – peer drinking (Windle, 2000), across several developmental periods from adolescence through young adulthood.
