title: Genetic and environmental effects on offspring alcoholism: new insights using an offspring-of-twins design.
abstract: BACKGROUND
  Although there is now considerable evidence that genetic effects play a critical role in the development of alcohol dependence (AD), theoretical and methodological limitations of this literature require caution in describing the etiology and development of this disorder.
  
  
  OBJECTIVE
  To disentangle genetic and environmental effects on AD by means of the infrequently used, yet potentially powerful, offspring-of-twins design.
  
  
  METHODS
  Offspring of twins.
  
  
  METHODS
  Male monozygotic and dizygotic twins concordant or discordant for AD and control pairs from the Vietnam Era Twin Registry were assessed, as were the offspring of these twins and the mothers of these offspring.
  
  
  METHODS
  Structured psychiatric interviews.
  
  
  METHODS
  Participants' psychiatric, alcohol abuse (AA), and AD histories (DSM-IV).
  
  
  RESULTS
  Offspring of monozygotic and dizygotic twins with a history of AD were significantly more likely to exhibit AA or AD than were offspring of nonalcoholic fathers. Offspring of an alcohol-abusing monozygotic twin whose co-twin was AD were also more likely to exhibit AD than were offspring of nonalcoholic twins. In contrast, offspring of an unaffected (ie, no history of abuse or dependence) monozygotic twin whose co-twin was AD were no more likely to exhibit AA or AD than were offspring of nonalcoholic twins.
  
  
  CONCLUSIONS
  These findings support the hypothesis that family environmental effects do make a difference in accounting for offspring outcomes, in particular, that a low-risk environment (ie, the absence of parental alcoholism) can moderate the impact of high genetic risk regarding offspring for the development of alcohol-use disorders.
authors.affiliation: Palo Alto Veterans Affairs Health Care System, Menlo Park, CA 94025, USA. tjacob@pgsp.edu
authors.forename: Theodore
authors.initials: T
authors.lastname: Jacob
authors.forename: Brian
authors.initials: B
authors.lastname: Waterman
authors.forename: Andrew
authors.initials: A
authors.lastname: Heath
authors.forename: William
authors.initials: W
authors.lastname: True
authors.forename: Kathleen K
authors.initials: KK
authors.lastname: Bucholz
authors.forename: Randy
authors.initials: R
authors.lastname: Haber
authors.forename: Jeff
authors.initials: J
authors.lastname: Scherrer
authors.forename: Qiang
authors.initials: Q
authors.lastname: Fu
mesh_terms: D000293:Adolescent; D000328:Adult; D000437:Alcoholism / Q000235:genetics* / Q000523:psychology; D002648:Child; D016241:Child of Impaired Parents / Q000523:psychology*; D004200:Diseases in Twins / Q000235:genetics*; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D006801:Humans; D016013:Likelihood Functions; D008297:Male; D008875:Middle Aged; D018570:Risk Assessment; D014429:Twins, Dizygotic / Q000235:genetics; D014430:Twins, Monozygotic / Q000235:genetics