Twin cohort associated_with risky sexual behavior

When twin pairs with differing ages at first use were considered, rVUS was more commonly reported in the twin reporting the earlier age at first use.

exposure of one member of the twin pair ... increased her likelihood of rVUS.

twins from concordant adolescent‑onset pairs were at the highest likelihood for reporting rVUS (DZ: 41.9%)

marginally increased likelihood for MZ twins to report rVUS, relative to their DZ counterparts