When firm causal inferences are drawn, it is often important to access very special samples. The present study used data from a sample of adolescents who are twins or siblings, and a sample of parents who are twins with adolescent offspring specifically designed to mirror the adolescent sample in order to investigate the mechanisms underlying the association between parental knowledge and adolescent externalizing behavior. We employed the ECOT approach in order to disentangle the direction of effect of the association as well as the underlying genetic and environmental influences of the association. Drawing from the two predominant theories in the literature, we hypothesized that the association between parental knowledge and adolescent externalizing behavior would be driven in part by direct environmental influences from parents to adolescents, and in part by evocative rGE, such that parental knowledge stems in part from adolescent disclosure and youth with heritable externalizing behavior would be less likely to disclose information on their whereabouts and activities.
