To confirm that differences in brain volumes among discordant pairs in the linear mixed models (Contrast 1) were non-significant due to familial matching rather than a reduction in sample size, we randomly paired each cannabis user from a same-sex discordant pair (N=89) with a sex-matched, unrelated unexposed individual. Paired t-tests were performed to compare volumes for these unrelated pairs, i.e. to remove the familial control while matching for sample size.
