Genetic influences on childhood competencies: A twin study

Objective: To estimate genetic, environmental, and rater contrast influences on parental reports of Activities, Social, School, and Total Competence scales of the Child Behavior Checklist (CBCL). Method: Parents of 492 twin pairs aged 8-12 years completed CBCLs, Genetic, shared and unique environmental, and rater bias effects were estimated for the Activities, Social, School, and Total Competence scales. Data on boys and girls were analyzed separately. Results: Moderate genetic influences were found only for the School scale (60%-76%), while shared environment accounted for most of the variance in Activities, Social, and Total Competence scales. Gender differences are reported. Similar to a prior twin study of CBCL problem syndromes, there was no evidence of rater bias. Conclusions: Estimates of genetic influence on these child competence domains were high for School Competence, while social competence and activity competence evidenced higher levels of shared environmental influences. Organization and wording of CBCL items may avoid rater biases in reporting. These findings have implications for interventions to improve school, social, and activities competence.