Problematic alcohol use polygenic scores were associated with escalation (linear slope) and quadratic curvature of HED, but not baseline levels (intercept). This is consistent with prior research linking parental AUD, which has a genetic component, to accelerated adolescent heavy drinking.43 It also reflects broader findings that genetic factors have little influence on alcohol initiation and misuse in early adolescence but become increasingly important over time in shaping alcohol use patterns.44 Contrary to our expectation, we did not find evidence that either parental separation or discord modified the effect of problematic alcohol use polygenic scores on the longitudinal course of HED. This indicates that the effect of parental separation or discord on HED baseline and the effect of polygenic loading for problematic alcohol use on the linear slope and quadratic curvature were unique and independent. These findings suggest that the longitudinal course of HED over time is influenced by both children’s polygenic predispositions and their exposure to familial stressors. Although the absence of significant gene–environment interaction effects on the longitudinal course of HED was contrary to our hypothesis, our observed pattern
