This pattern of effects is consistent with prior evidence that there are overlapping sets of genetic influences that contribute to alcohol problems, relationship discord, and divorce22, and indicates that even nontransmitted alleles influence offspring alcohol outcomes via parental relationship discord. It is notable that indirect genetic effects mediated through parental relationship discord were observed across the range of offspring alcohol use behaviors ranging from initiation to meeting clinical criteria. In contrast, indirect genetic effects mediated through parental divorce were observed for initiation and intoxication only. This suggests that while both parental relationship discord and divorce are involved in the pathways to alcohol use and misuse, there may be important differences in these factors in terms of risk for clinically significant alcohol use problems. This may reflect the more acute disruptions to parenting associated with divorce (e.g., lower parental monitoring) that facilitate adolescents’ access to alcohol15 versus the potentially more pervasive effects of exposure to high levels of parental relationship discord7.
