title: Conduct problems in children and adolescents: a twin study.
abstract: BACKGROUND
  Evidence supports a genetic influence on conduct problems as a continuous measure of behavior and as a diagnostic category. However, there is a lack of studies using a genetically informative design combined with several different informants and different settings.
  
  
  OBJECTIVE
  To examine genetic and environmental influences on conduct problems rated by parent and teacher reports and self-reports and to determine whether their ratings reflect a common underlying phenotype.
  
  
  METHODS
  A twin study design was used to examine conduct problem scores from ratings by teachers, parents, and twins themselves.
  
  
  METHODS
  General community.
  
  
  METHODS
  Twins aged 5 to 17 years participating in the Cardiff Study of All Wales and North England Twins (CaStANET) project.
  
  
  METHODS
  Conduct problem scale from the Strengths and Difficulties Questionnaire.
  
  
  RESULTS
  Conduct problem scores were significantly heritable based on parent and teacher reports and self-reports. Combining data from all 3 informants showed that they are rating a common underlying phenotype of pervasive conduct problems that is entirely genetic, while teacher ratings show separate genetic influences that are not shared with other raters.
  
  
  CONCLUSIONS
  Conduct problems are significantly heritable based on parent and teacher reports and self-reports, and are also influenced by environmental effects that impinge uniquely on children from the same family. There is a cross-situational conduct problems' phenotype, underlying the behavior measured by all informants, that is wholly genetic in origin. No significant influence of shared environmental effects was found.
authors.affiliation: Department of Psychological Medicine, University of Wales College of Medicine, Heath Park, Cardiff. scourfieldj@cardiff.ac.uk
authors.forename: Jane
authors.initials: J
authors.lastname: Scourfield
authors.forename: Marianne
authors.initials: M
authors.lastname: Van den Bree
authors.forename: Neilson
authors.initials: N
authors.lastname: Martin
authors.forename: Peter
authors.initials: P
authors.lastname: McGuffin
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D002648:Child; D002653:Child Behavior Disorders / Q000175:diagnosis / Q000453:epidemiology / Q000235:genetics; D002675:Child, Preschool; D019955:Conduct Disorder / Q000175:diagnosis* / Q000453:epidemiology / Q000235:genetics*; D004200:Diseases in Twins / Q000175:diagnosis* / Q000453:epidemiology / Q000235:genetics*; D004739:England / Q000453:epidemiology; D005260:Female; D006801:Humans; D008297:Male; D008957:Models, Genetic; D010290:Parents / Q000523:psychology; D010555:Personality Inventory; D010641:Phenotype; D012931:Social Environment; D011795:Surveys and Questionnaires; D013663:Teaching; D014429:Twins, Dizygotic / Q000235:genetics; D014430:Twins, Monozygotic / Q000235:genetics; D014852:Wales / Q000453:epidemiology