that the interaction is most consistent with a diathesis-stress model (Zuckermann 1999), which suggests that some individuals are more vulnerable to adverse effects of environmental stressors (e.g., delinquent peers) due to their genetic composition. That is, adolescents with the GG genotype do not differ from A-carriers at low levels of peer delinquent; it is only when exposed to adverse social contexts (i.e., higher levels of contact with delinquent peers) that differences emerge. This is in contrast to the differential susceptibility model (Belsky et al. 2009), which suggests that adolescents with genotypes traditionally conferring risk may actually be more affected by adverse as well as adaptive environments. Failure to detect significant differences between GG and A-carriers in the low peer delinquent scenario may be explained by the fact that low delinquent peer contact does not represent involvement with a supportive environment (e.g., peers involved in academics or church). Furthermore, the lower bound of region of significance was outside the range of responding. Another reason may be that the sample is overrepresented by subjects associating with peers with high levels of delinquency, thus with a higher power to detect significant interactions in the upper bound. We cannot rule out the possibility that
