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. Objectives: 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. Design: A twin study design was used to examine conduct problem scores from ratings by teachers, parents, and twins themselves. Setting: General community. Participants: Twins aged 5 to 17 years participating in the Cardiff Study of All Wales and North England Twins (CaStANET) project. Main Outcome Measures: 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.