Schlosser, Lidral, & Reich, 1999; Legrand, McGue, & Iacono, 1999); relationships with antisocial peers (Zucker, Donovan, Masten, Mattson, & Moss, 2008); and prior smoking (Chen et al., 2002). From this existing list of predictors, Kuperman et al. (2005) identified 63 contained within the adolescent version of the Semi-Structured Assessment for the Genetics of Alcoholism (SSAGA) interview. These variables were used in a series of multiple regression models to identify those significantly related to the self-reported age of drinking initiation in a subsample of 440 adolescent drinkers from the Collaborative Study on the Genetics of Alcoholism (COGA). From this pool, 3 variables – age at interview, number of DSM-IV non-drinking related conduct disorder symptoms (referred to as CD from this point), and the number of adult alcohol-dependent (AD) siblings – formed the most parsimonious model and explained 45% of the variance of age of first drink. Kuperman et al. (2013) subsequently employed these variables along with two additional SSAGA variables (whether most of a subject's best friends drank, and if the subject smoked a cigarette before initiating drinking) and eight scale scores from the commonly used Achenbach Youth Self Report (Achenbach & Rescorla, 2001) to predict the onset of alcohol initiation
