Using the COGEND sample we recently reported another interaction with rs16969968 in which the risk of nicotine dependence associated with the AA genotype at rs16969968 was significantly greater among those with low parent monitoring compared to higher monitoring [33]. It is reasonable to expect that low parent monitoring may increase opportunities to affiliate with smoking peers and thereby increase risk of smoking. Indeed, the commentary accompanying Chen et al. [33], suggested this possibility [34]. In the COGEND sample we find a weak but statistically significant correlation between lower parent monitoring and a larger number of peers who smoked (r = 0.15, p < 0.0001). Thus it might be hypothesized that there would be greater risk of nicotine dependence associated with the A allele at rs16969968 when parent monitoring is lower and peer smoking higher. However, this was not what was observed; the probability of nicotine dependence remained high and relatively constant across numbers of smoking peers among those with the AA genotype. To explore these divergent findings we estimated models including both the parent monitoring scale and H.S. peer smoking,
