Contrary to our expectations, there was no indirect effect of genetic risk on adolescent externalizing at T2 via parental knowledge from T1. This seems to be consistent with some evidence from the twin literature that suggests parental knowledge is associated with adolescent externalizing via a direct environmental influence independent of genetic influences (Marceau et al. 2015). It is also possible that the lack of significant indirect effects via parenting from T1 may mean that parental knowledge may have more of a concurrent effect than a lagged effect. In fact, in looking at the within-time correlations, the magnitude of correlation between T1 parental knowledge and T1 externalizing was smaller as compared to the correlation between T1 peer substance use and T1 externalizing, and, thus, there is even less predictive variance to be carried over. It is interesting to also note that higher parental knowledge at T1 was associated with decreased perceived peer substance use at T2, which is correlated with T2 externalizing behavior. Thus, it is possible that the lagged effect of parental knowledge might not be operating on externalizing behavior
