parenting and other ‘environmental’ variables suggested that self-report and informant-report yielded similar heritability estimates and that observer-reports yielded lower estimates. They argued that this is likely due to unreliability of observer reports, which were based on ten minutes or less of observation. Therefore, they concluded that twin studies of environmental variables largely reflect ‘actual behavior’ rather than ‘only perceptions’. In a separate study, maternal reports of family environment were modestly to moderately correlated over a twenty-five year time span (Finkel & McGue, 1993). Second, despite the large sample size, power was an issue, as evidenced by the fact that the homogeneity and heterogeneity models fit similarly despite substantially different parameter estimates across the sexes and the lack of power to distinguish A and C in the univariate models. Considered individually, none of the estimates of A, C, or T was significantly greater than zero. Almost half of the participants reported no experiences of maltreatment, and the low prevalence of sexual maltreatment precluded consideration of sex differences in the magnitude of the parameter estimates.
