differ in cross sectional studies as compared with studies of the trajectories of ASD across the life span. This may also apply to ADHD, because twin studies of ADHD have shown that the heritability of ADHD in youth is greater than that in adults. 108 Prospective twin studies have shown that different genes may be associated with baseline symptoms compared with persistence of ADHD across development, but few of these studies have investigated interactions with sex. 109 However, in contrast to family studies, twin studies of ADHD have found equal magnitude of heritability in males and females.
