• In a sample of 242 male and 201 female adoptees who had been separated at birth from biologic parents, adult adoptee diagnoses of alcohol abuse, drug abuse and antisocial personality were correlated with biologic and environmental factors. Three etiologic relationships with drug abuse were found: (1) drug abuse was highly correlated with antisocial personality, which in turn was predicted from antisocial biologic background; (2) a biologic background of alcohol problems predicted increased drug abuse in adoptees who did not have antisocial personalities; and (3) environmental factors of divorce and psychiatric disturbance in the adoptive family were associated with increased drug abuse.
Cadoret RJ, Troughton E, O'Gorman TW, Heywood E. An Adoption Study of Genetic and Environmental Factors in Drug Abuse. Arch Gen Psychiatry. 1986;43(12):1131-1136. doi:10.1001/archpsyc.1986.01800120017004