Other studies with ES twins have shed additional light on the development of cognitive ability and educational attainment. We have reported that high cognitive ability is heritable in adolescence. A modest shared environmental effect is also evident, both for cognitive ability in general and for especially high ability (Haworth et al., 2009b; Kirkpatrick et al., 2009). Academic achievement has been examined in a series of studies, Johnson and colleagues (2005; 2006; in press). This work has explored the complexity of gene-environment interplay associated with the development of academic achievement from pre-adolescence through adolescence and into young adulthood.
