Participants were assessed for nicotine and alcohol dependence. The alcohol related questions were derived from the Semi-Structured Assessment for the Genetics of Alcoholism (SSAGA-II). The SSAGA-II is a comprehensive, diagnostic interview which was developed for Collaborative Study on Genetics of Alcoholism (COGA) (Bucholz et al., 1994; Hesselbrock et al., 1999). Participants were assessed for alcohol dependence on DSM-IV classification system and the maximum drinks that a person ingested in a 24 period was queried.
