Importantly, even within MZ pairs discordant for adolescent cannabis use, there was a consistent elevation in the likelihood of rVUS in the adolescent-onset twin relative to their genetically identical never/later-onset user co-twin (OR 2.25, 95% CI [1.14-4.44]). Adjustment for covariates did not attenuate this association (Table 2), suggesting that factors other than those shared by members of MZ twin pairs, including shared genetic and environmental influences, significantly contributed to the relationship between adolescent cannabis use and rVUS.
