title: Drinking by parents, siblings, and friends as predictors of regular alcohol use in adolescents and young adults: a longitudinal twin-family study.
abstract: OBJECTIVE
  The aim of this study was to examine whether the drinking habits of parents, siblings, and friends were related to regular drinking in adolescents and young adults, cross-sectionally as well as longitudinally.
  
  
  METHODS
  Data of 12-30-year-old twins from the Netherlands Twin Register were analysed. Information on regular drinking was collected in 1993, 1995, and 2000. Logistic regression analyses were conducted on cross-sectional data of 1993 (N=3760), short-term longitudinal data of 1993-95 (N=2919), and the long-term longitudinal data of 1993-2000 (N=1779).
  
  
  RESULTS
  Results show that age, sex, and one's own previous drinking habits were important predictors of later-life regular drinking. Drinking habits of parents showed small but persistent positive associations. Alcohol use of the co-twin was strongly related to alcohol use of the participants, especially in the cross-sectional analyses, while alcohol use of additional siblings other than the co-twin was relatively unimportant. Cross-sectionally, friends' alcohol use showed a high association with regular drinking, but this association decreased over time.
  
  
  CONCLUSIONS
  Cross-sectional analyses showed that a substantial part (29%) of the variance in regular drinking habits of adolescents and young adults was explained by the drinking habits of family members and friends, in particular, by drinking of co-twins and friends. But, over time, drinking by family members and friends could only explain a relatively small part (4-5%) of the variance in adolescents' and young adults' alcohol use.
authors.affiliation: Behavioural Science Institute, Radboud University Nijmegen, The Netherlands. e.poelen@pwo.ru.nl
authors.forename: Evelien A P
authors.initials: EA
authors.lastname: Poelen
authors.forename: Ron H J
authors.initials: RH
authors.lastname: Scholte
authors.forename: Gonneke
authors.initials: G
authors.lastname: Willemsen
authors.forename: Dorret I
authors.initials: DI
authors.lastname: Boomsma
authors.forename: Rutger C M E
authors.initials: RC
authors.lastname: Engels
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000428:Alcohol Drinking / Q000453:epidemiology / Q000523:psychology*; D002648:Child; D003430:Cross-Sectional Studies; D003627:Data Interpretation, Statistical; D005190:Family / Q000523:psychology*; D005260:Female; D033062:Friends / Q000523:psychology*; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D009426:Netherlands / Q000453:epidemiology; D012737:Sex Factors; D035781:Siblings / Q000523:psychology*; D011795:Surveys and Questionnaires; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic