title: Sexual behavior in young adulthood: a population-based twin study.
abstract: OBJECTIVE
  With behavior genetic analyses of data from young adult twins, we evaluated theoretical perspectives that differentially emphasize biological dispositions, social/cultural factors, or universal pathways to explain individual differences in sexual behaviors.
  
  
  METHODS
  We fit biometric sex limitation models to three aspects of sexual behavior reported by 4,925 Finnish twins ages 23-27.
  
  
  METHODS
  From a postal questionnaire, we obtained self-report information on initiation/abstinence of sexual intercourse, onset age, and number of sexual partners.
  
  
  RESULTS
  Genetic and non-shared environmental influences were significant for all three measures. There were trends for common environmental influences on initiation and, in females, age at first intercourse. Some differential effects in males and females were found. Results comparing onset age and number of partners among experienced twins from pairs concordant and discordant for initiation found genetic and environmental influences on initiation/abstinence overlapped those found for the other aspects of sexual behavior.
  
  
  CONCLUSIONS
  These results document genetic variation in individual differences in sexual behavior of young adults. Incorporating genetic dispositions into integrated models of sexual behavior will facilitate more effective health promotion and risk taking intervention.
authors.affiliation: Department of Psychological and Brain Sciences, Indiana University, USA.
authors.forename: Brian
authors.initials: B
authors.lastname: Mustanski
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Viken
authors.forename: Jaakko
authors.initials: J
authors.lastname: Kaprio
authors.forename: Torsten
authors.initials: T
authors.lastname: Winter
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Rose
mesh_terms: D000328:Adult; D001699:Biometry; D005260:Female; D005387:Finland; D014644:Genetic Variation; D006801:Humans; D008297:Male; D012725:Sexual Behavior / Q000706:statistics & numerical data; D011795:Surveys and Questionnaires; D018433:Twin Studies as Topic