To the extent that this adolescent/young adult female sample exhibited lower rates of alcohol use (Brady & Randall, 1999) and somewhat greater religiousness (Hood et al., 1996) as compared to male samples, conservative estimates of alcohol use and some additional sensitivity in the detection of the R/S effects would be expected. Concerning use of a twin sample, since twins have not been found to be significantly different from nontwins on a variety of characteristics including alcohol abuse and alcohol dependence (Johnson, Krueger, Bouchard, & McGue, 2002), these findings can be considered generalizable to nontwin populations. As well, since the target sample was all live-born twin pairs in Missouri, this sample can be considered representative of the larger population from which they were drawn. Note that the twin feature of this dataset was not used in current analyses, but the issue of possible nonindependence of observations was addressed (see Data Analysis).
