COGA participants came from alcohol dependent probands identified through alcohol treatment programs at six U.S. sites and were invited to participate if they had a sufficiently large family (usually sibships > 3 with parents available) with two or more members in the COGA catchment area (Begleiter et al., 1995; Edenberg, 2002). The Institutional Review Boards at all sites approved this study and written consent was obtained from all participants. A portion of the original COGA participants were assessed twice, and a subset of the adolescent and young adult offspring in COGA families have been assessed multiple times since 2004 (Bucholz et al., 2017). Participants completed the Semi-Structured Assessment for the Genetics of Alcoholism (SSAGA), a valid and reliable polydiagnostic interview (Bucholz et al., 1994). Those 18 years of age or older received the adult SSAGA and those who were under the age of 18 received an adolescent version of the SSAGA designed for those between ages 12–17 (Bucholz et al., 1994; Hesselbrock et al., 1999). We used data from the interview where participants endorsed the maximum total number of DSM-IV
