Separate moderated multiple regression analyses using the adolescent subsample indicated that parental monitoring and peer substance use moderated polygenic risk to predict the externalizing disorder composite after controlling for gender, age, and the main effects of the polygenic score and parental monitoring and peer substance use. However, we note that the moderation effect was only marginally significant for parental monitoring [Bparents × polygene = -1.30, t(154) = -1.88, p = 0.06, R2 = 1%; Bpeers × polygene = 1.81, t(155) = 2.68, p < .01, R2 = 2%]. Genetic effects were more pronounced at low levels of parental monitoring and high levels of peer substance use compared to high levels of parental monitoring and low levels of peer substance use (Figure 3).
