AUDs are moderately heritable (~50%) [7], with most of the heritability of AUD shared with other externalizing phenotypes [8–10]. Externalizing generally refers to a broad liability towards behavioral disinhibition and dysregulation. The externalizing spectrum includes disorders such as attention-deficit/hyperactivity disorder (ADHD), conduct disorder, substance use disorders, and antisocial behavior personality disorder, as well as personality traits like impulsivity and sensation seeking [10–12]. Prior research estimates that the majority of the genetic variance for AUD is shared with other externalizing disorders with a much smaller proportion of genetic variation specific to alcohol use outcomes [8]. Additionally, genetic influences on alcohol use outcomes change over time, with externalizing liability being more important in adolescence and alcohol-specific risk becoming more important as individuals age [13, 14]. In total, research on the etiology of AUD suggests differing pathways through which problems can develop.
