Generalist Genes: Genetic Links Between Brain, Mind, and Education

Abstract

Genetics contributes importantly to learning abilities and disabilities-not just to reading, the target of most genetic research, but also to mathematics and other academic areas as well. One of the most important recent findings from quantitative genetic research such as twin studies is that the same set of genes is largely responsible for genetic influence across these domains. We call these "generalist genes" to highlight their pervasive influence. In other words, most genes found to be associated with a particular learning ability or disability (such as reading) will also be associated with other learning abilities and disabilities (such as mathematics). Moreover, some generalist genes for learning abilities and disabilities are even more general in their effect, encompassing other cognitive abilities such as memory and spatial ability. When these generalist genes are identified, they will greatly accelerate research on general mechanisms at all levels of analysis from genes to brain to behavior.

Fig. 1

Multivariate genetic model for trait X and trait Y for one individual from a twin pair. (The actual model depends on cross-trait twin correlations for MZ and DZ twins, but the other member of the twin pair is not shown here.) Variance in each trait is divided into that due to latent additive genetic influences (A), shared environmental influences (C), and nonshared environmental influences (E) with the subscripts X and Y denoting scores on traits X and Y, respectively. Paths, represented by lowercase letters (a, c, and e), are standardized regression coefficients and are squared to estimate the proportion of variance accounted for. For example, a_X² is heritability, the proportion of phenotypic variance explained by genetic variance. Correlations between the latent genetic, shared environmental, and nonshared environmental influences are denoted by r_A, r_C, and r_E.

Fig. 2

Genetic model-fitting results within three domains of English at 7, 9, and 10 years.

Fig. 3

Genetic model-fitting results among English, mathematics, and science at 7, 9, and 10 years.

Fig. 4

General cognitive ability (g) and learning abilities: genetic model-fitting results among g, English, mathematics, and science at 7, 9, and 10 years.