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.
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.
A twin study design was used to examine conduct problem scores from
ratings by teachers, parents, and twins themselves.
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.
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.
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.