Preliminary analyses indicate significant differences in parental age by risk status, F (3, 1281) = 10.82, p < .0001. Differences in offspring age by risk status were also significant, F (3, 2488) = 6.30, p < .001. Results of post-hoc tests suggest that parents from control families (Group 4) are older on average than parents from families where either the parent or parent's MZ or DZ co-twin is AUD+ (Groups 1, 2 and 3). Although offspring in Group 4 are also older than offspring whose parent is AUD+ (Group 1), both groups are indistinguishable from offspring whose parent's MZ or DZ co-twin is AUD+ (Groups 2 and 3).
