A twin study of inattentive, aggressive, and anxious/depressed behaviors

Objective: To estimate genetic, environmental, and rater contrast influence s on parental report of Attention Problems (AP), Aggressive (Agg), and Anxi ous/Depressed (AxD) behaviors of 492 twin pairs assessed with the Child Beh avior Checklist. Method: A parent (92% mothers) of twins aged 8 to 12 years completed the Child Behavior Checklist. Genetic, shared and unique environ mental, and rater bias effects were estimated for the AP, Agg, and AxD synd romes. Data on boys and girls were analyzed separately. Results were compar ed to prior research on related DSM disorders. Results: Estimates of geneti c influences on AP (60%-68%), Agg (70%-77%), and AxD (61%-65%) were high fo r both sexes, but lower for AP than prior findings using DSM attention-defi cit hyperactivity disorder (ADHD). However, unlike equivalent analyses of D SM ADHD based on parental report, there was no evidence of rater bias. Conc lusions: Estimates of genetic influence on these common child psychopatholo gical domains were high. There was no evidence of rater contrast effects. T hese findings have implications for diagnosis, particularly when assessing families with multiple children.