A TWIN STUDY OF COMPETENCE AND PROBLEM BEHAVIOR IN CHILDHOOD AND EARLY ADOLESCENCE

The Child Behavior Checklist (CBCL) was completed by parents of 181 pa irs of same-sex twins ages 7-15 (mean age 11.0 years). Correlations be tween scores on the CBCL scales for 99 pairs of monozygotic twins and 82 pairs of dizygotic twins indicated significant genetic influences t hat varied according to the specific area of competence and problem be havior. Model-fitting estimates derived from multiple regression analy ses indicated significant genetic influence on competence in school an d on all areas of problem behavior. In addition, significant shared en vironmental influence was detected for amount and quality of participa tion in activities, quality of social relationships, performance in sc hool, anxiety/depression, and delinquent behaviour. Implications for f uture work on the mechanisms underlying these effects are discussed.