Clearly, there is a need for alternative methodologies to examine effects of parental separation in African American families, and particularly approaches where matching on risks upstream of separation, especially parental alcoholism, can be achieved. In the present study, statistical power is limited due to our much smaller sample of African relative to European ancestry twin-families. However, between-family matching in samples of sufficient size, where parental alcoholism and other pertinent risk-factors are also assessed, should be pursued. Another approach is to employ within-family matching, for example, comparing timing of first sex in children of siblings or twins discordant for separation or divorce. Within-family matching provides powerful control of unmeasured confounds in the parental generation. While such studies exist (e.g.,[36,37]), to our knowledge none report effects of parental separation specific to African American families.
