Adolescents with a genetic liability for the development of externalizing problems may also be more prone to choose or elicit affiliations with peers who show patterns of behavior similar to their own. Such selection falls in line with the early theoretical work of Scarr and McCartney (1983), who posited active or evocative gene-environment correlations (Plomin et al., 1977) as a corollary to the increased autonomy that accompanies the transition into adolescence. In relation to the effects found here, we can be confident that the extent to which social influence exacerbates one’s genetic liability for the development of externalizing problems (i.e., gene-environment interaction) was unadulterated by social selection, at least with respect to CHRM2, given the absence of an association between genotype and peer group antisocial behavior. It is not clear, however, whether the social influence observed in the present study reflects deviancy training (i.e., behavioral modification in response to peers’ responses; Capaldi et al., 2001; Dishion et al., 1995), peer modeling (i.e., behavioral initiation in response to peers’ behaviors; Fromme, 1983), or both. Thus, future examination of the moderating role
