Both other substance use (Guxens et al., 2007) and psychopathology (Pardini et al., 2007) have been associated with alcohol involvement; therefore, cannabis use, tobacco use, conduct disorder (CD), and major depressive disorder (MDD) were considered as covariates. Tobacco initiation (age of onset) was defined as the first age at which the participant used/tried smoking tobacco. Cannabis initiation (age of onset) was defined as the first age at which the participant used/tried cannabis. Conduct disorder was defined as meeting three or more conduct disorder symptoms in a 12-month period prior to the age of 15. Major Depressive Disorder criteria was met if 5 or more major depressive symptoms during the same 2-week period (along with dysphoria or anhedonia) were reported as occurring for more than 2 weeks with age of onset defined as age when first met full criteria. Parental characteristics: To consider socio-economic status, mother’s reports of familial household income (defined as < $30,000, $30,000 – $74,999, and ≥ $75,000) and parental education were both included in models as a proxy. Variables representing mother’s and father’s education levels were created
