Generalist Genes Research Articles

Reading and General Cognitive Ability: A Multivariate Analysis of 7-Year-Old Twins

We examined the association between reading and general cognitive ability (g) in a population-based sample of 6,476 pairs of 7-year-old twins. Additive genetic influences largely accounted for individual differences in reading and the covariation between reading and g. Furthermore, both genetic and shared environmental influences on reading and g correlate highly. Nonetheless, after accounting for genetic and environmental influences shared with g, there remain strong genetic and shared environmental influences specific to reading. Nonshared environmental influences are largely reading specific. There is also suggestive evidence that reading may have a causal effect on g. The results support an emerging consensus that individual differences in reading are likely to reflect genes that contribute to variation in other complex abilities reflected by g ("generalist genes"), as well as genes and environments that influence reading independent of g.

Generalist Genes and Learning Disabilities.

The authors reviewed recent quantitative genetic research on learning disabilities that led to the conclusion that genetic diagnoses differ from traditional diagnoses in that the effects of relevant genes are largely general rather than specific. This research suggests that most genes associated with common learning disabilities--language impairment, reading disability, and mathematics disability--are generalists in 3 ways. First, genes that affect common learning disabilities are largely the same genes responsible for normal variation in learning abilities. Second, genes that affect any aspect of a learning disability affect other aspects of the disability. Third, genes that affect one learning disability are also likely to affect other learning disabilities. These quantitative genetic findings have far-reaching implications for molecular genetics and neuroscience as well as psychology.