Table 3 shows the prevalence of rVUS in MZ and DZ twin pairs concordant and discordant for adolescent cannabis use. Regardless of zygosity, twins from concordant adolescent-onset pairs were at the highest likelihood for reporting rVUS (MZ: 47.1%; DZ: 41.9%) while twin pairs where neither twin reported adolescent cannabis use exhibited the lowest rates of rVUS (MZ: 22.4%; DZ: 18.7%). The prevalence of rVUS was considerably higher in the adolescent-onset members of the discordant pairs (MZ: 39.1%; DZ: 34.5%) than in their never/late-onset user co-twins (MZ: 26.1%; DZ: 23.5%). Consistent with this observation, the adolescent onset cannabis-using twin member was at two times increased odds of reporting rVUS relative to their never or later-onset user co-twin (Table 2).
