Inclusion and exclusion criteria, recruitment, and consent procedures are detailed elsewhere (20). Children ranged in age from 5 to 15 years (χ2 = 9.7, SD = 2.7), with five being the lower age limit when conduct symptoms are reported to first appear (22). The sample had more male subjects (66%) because heterozygous females were excluded. Twenty-four percent: of subjects were European American (EA), 25% Hispanic, 31% African American (AA), and 19% biracial. Maltreated and control groups did not differ in terms of age (t = −1.27, df= 112, ns), sex (χ2 .7, df = 1, ns), or ethnicity (χ2 = 5.2, df= 4, ns). The 114 children were from 85 families with various numbers of siblings and half-siblings (range: 1–4) in each family, with a comparable number of siblings included in the study in both of the groups (F = 1.6, ns, Maltreated: 1.6 ± .7; Control: 1.8 ± 1.0).
