As there were no correlated common E factors, unique environmental covariance between SELF and PEER was limited to that derived from causal pathways. Estimates for these paths were low, and in some cases were not significantly different from 0, though tests indicated that causal paths in either direction could not be removed completely from the model (Table 2, Models 14 and 16). While the final model demonstrated that causal influences are relevant with regards to non-shared environmental factors, the majority of covariation between SELF and PEER was attributable to the correlation between the genetic and shared environmental common factors (Supplementary Table 2). Overall, A covariance increased over time (alongside heritability), while C covariance decreased.
