The participants included in the present study were 18- to 25-year-old relatives of alcohol dependent probands who participated in the Collaborative Study on the Genetics of Alcoholism (COGA) project. COGA is a multicenter, longitudinal project that began in 1989 with recruitment at six centers (Indiana University, Indianapolis; State University of New York at Brooklyn; University of California-San Diego and Scripps Institute, San Diego; University of Connecticut, Farmington; University of Iowa, Iowa City; and Washington University, St. Louis, Missouri). The goal of COGA is to identify the genes that impact risk for alcoholism and alcohol-associated characteristics and behaviors (Edenberg, 2002). Adults receiving treatment for alcohol dependence were identified through public and private treatment centers. Biological relatives of alcohol dependent probands aged 7–25 years were targeted for recruitment and reassessment. The present analyses focused on the young adult sample, aged 18–25. Individuals younger than 18 years of age were not queried on items related to sexual history and were thus excluded from the present study. Because the focus of COGA was on systematic ascertainment of alcohol dependent participants followed by interviews of their relatives, the sample studied here was not matched for SES.
