like-sex twin pairs and significant association with psychiatric sequelae and parental risk factors (Dinwiddie et al. 2000; McLaughlin et al. 2000). Examination of discordant pairs found no evidence for retrospective bias in the association of CSA with parental rejection (McLaughlin et al. 2000). The prevalence of CSA in our sample is higher than is typical for community samples, a likely result of enrichment for heavy smoking. Because of this enrichment, additional studies will be necessary to determine whether our results will generalize to samples representative of the general population. Post-hoc analyses of genetically informative data on ancestry from a partially overlapping GWAS revealed that two families (N=4 individuals in total) are outliers on the basis of ancestry. The ACFS of these families does not differ significantly from the remainder of the sample; dropping these 4 individuals has very minimal effect on either interaction term point estimates or p values.
