Common and specific gender influences on individual differences in reading performance: a twin study

In order to test the hypothesis of a gender-based differential etiology of individual differences in reading performance, data from two research-identified samples of twins (638 pairs of twins in which at least one member of the pair had a positive school history of reading problems and a comparison sample of 414 twin pairs with no history of reading problems) were fitted to a structural equation model of sex-limitation. When a parsimonious model that constrained the genetic correlation between reading performance of males and females in the proband group to be equal to that in the control group was fitted to the data, the resulting pooled estimate of the genetic correlation (0.59) was significantly greater than zero and less than one (0.28–0.88, 95% confidence interval). Thus, the etiology of individual differences in reading performance is due to both common and gender-specific genetic influences.