In COGA, which comprised a family design (rather than a twin design), affectation status of relatives (particularly parents) reflects both inherited and environmental risk. Thus, although it was possible to specify inherited influences in MOTWIN, the best that could be done in COGA was to parameterize familial risk, which represents an amalgam of genetic and environmental risk, against which independent effects of maltreatment can be examined. Not surprisingly, children in COGA with higher levels of familial risk ascertained in this way were, in addition, at higher risk for child maltreatment. We note that an ordinal index of presumptive risk for maltreatment using SES and life event data obtained throughout the multisite COGA network was found NOT to significantly correlate with official-report maltreatment data for children at the Washington University site.
