This is the first large-scale epidemiologic study of maltreatment and antisocial development to simultaneously control for inherited risk and employ administrative data (official-report) as the method of ascertaining maltreatment. Significant additive (though not interactive) effects of inherited liability and maltreatment were observed. The results in our large twin sample were substantially confirmed in an enriched clinical sample of children at combined genetic and environmental risk for antisocial development, with one notable difference. In the epidemiologic twin sample, the largest discrepancy in risk as a function of maltreatment severity occurs at the level of reporting of maltreatment, irrespective of whether the reports are substantiated. In the clinical sample, the greatest contrast was observed between children who were reported and those whose reports were actually substantiated, although we note that even among the non-maltreated children in the COGA sample, the prevalence of conduct disorder symptomatology was elevated (21%). It is possible that within the latter group—which comprised more densely affected families—either the high prevalence of child maltreatment reports (much higher than that observed in any of the twin groupings) or the nature
