Conflict of interest statement: No conflicts declared.
Generalist genes and learning disabilities: a multivariate genetic analysis of low performance in reading, mathematics, language and general cognitive ability in a sample of 8000 12-year-old twins
Article first published online: 1 JUL 2009
© 2009 The Authors. Journal compilation © 2009 Association for Child and Adolescent Mental Health
Journal of Child Psychology and Psychiatry
Volume 50, Issue 10, pages 1318–1325, October 2009
How to Cite
Haworth, C. M.A., Kovas, Y., Harlaar, N., Hayiou-Thomas, M. E., Petrill, S. A., Dale, P. S. and Plomin, R. (2009), Generalist genes and learning disabilities: a multivariate genetic analysis of low performance in reading, mathematics, language and general cognitive ability in a sample of 8000 12-year-old twins. Journal of Child Psychology and Psychiatry, 50: 1318–1325. doi: 10.1111/j.1469-7610.2009.02114.x
- Issue published online: 17 SEP 2009
- Article first published online: 1 JUL 2009
- Manuscript accepted 20 March 2009
- Learning disability;
- behavioral genetics;
- generalist genes
Background: Our previous investigation found that the same genes influence poor reading and mathematics performance in 10-year-olds. Here we assess whether this finding extends to language and general cognitive disabilities, as well as replicating the earlier finding for reading and mathematics in an older and larger sample.
Methods: Using a representative sample of 4000 pairs of 12-year-old twins from the UK Twins Early Development Study, we investigated the genetic and environmental overlap between internet-based batteries of language and general cognitive ability tests in addition to tests of reading and mathematics for the bottom 15% of the distribution using DeFries–Fulker extremes analysis. We compared these results to those for the entire distribution.
Results: All four traits were highly correlated at the low extreme (average group phenotypic correlation = .58). and in the entire distribution (average phenotypic correlation = .59). Genetic correlations for the low extreme were consistently high (average = .67), and non-shared environmental correlations were modest (average = .23). These results are similar to those seen across the entire distribution (.68 and .23, respectively).
Conclusions: The ‘Generalist Genes Hypothesis’ holds for language and general cognitive disabilities, as well as reading and mathematics disabilities. Genetic correlations were high, indicating a strong degree of overlap in genetic influences on these diverse traits. In contrast, non-shared environmental influences were largely specific to each trait, causing phenotypic differentiation of traits.