This study integrated pre-existing data from three sources: Official records of the Missouri Department of Social Services (DSS) covering the years from 1981 to 2008 (source 1) were cross-referenced with a) behavioral data from the Missouri Twin Registry (MOTWIN, source 2; birth years 1981–1996; study years 1989–2008), an epidemiologic twin sample ascertained from birth records; and b) behavioral and family history data on 7–21 year old family members of adults enrolled in the Collaborative Study on the Genetics of Alcoholism (COGA, source 3; birth years 1981–1996; study years 1989–2008), these adults were ascertained on the basis of alcohol dependence.
