Importantly, GxE studies as they relate to peer influences on adolescent alcohol use behaviors have not widely controlled for concomitant processes that may confound their effects. For instance, adolescents and their closest friends strongly model and influence each other’s attitudes and perceptions towards drinking (i.e., socialization effects; Jaccard et al., 2005; Brechwald and Prinstein, 2011). Close friends are typically embedded within a broader peer group (e.g., school settings) and this broader peer context influences the magnitude of socialization effects from close friends (Urberg et al., 1995; Brechwald and Prinstein, 2011). Furthermore, socialization effects are also influenced by parental factors; the negative effects of close friends’ substance use are amplified when the quality of the parent-child relationship is strained (Jaccard et al., 2005). Thus, without accounting for concomitant processes (e.g., broader peer group and parental relationship), previous findings in the peer substance use literature more generally may have overestimated the effects of peer influences (Jaccard et al., 2005).
