The Genetic and Environmental Origins of Learning Abilities and Disabilities in the Early School Years: Monographs of the Society for Research in Child Development

in education and child development, little is known

about their genetic and environmental origins in the

early school years. We report results for English (which

includes reading, writing, and speaking), mathematics,

and science as well as general cognitive ability in a large

and representative sample of U.K. twins studied at 7, 9,

and 10 years of age. Although preliminary reports of

some of these data have been published, the purpose of

this monograph is to present new univariate, multivariate,

and longitudinal analyses that systematically examine

genetic and environmental influences for the entire sample

at all ages for all measures for both the low extremes

(disabilities) and the entire sample (abilities).

English, mathematics, and science yielded similarly

high heritabilities and modest shared environmental

influences at 7, 9, and 10 years despite major changes

in content across these years. We draw three conclusions

that go beyond estimating heritability. First, the abnormal

is normal: low performance is the quantitative extreme

of the same genetic and environmental influences

operate throughout the normal distribution. Second, continuity

is genetic and change is environmental: longitudinal

analyses suggest that age-to-age stability is primarily

mediated genetically whereas the environment contributes

to change from age to age. Third, genes are generalists

and environments are specialists: multivariate analyses

indicate that genes largely contribute to similarity

in performance within and between the three domains--

and with general cognitive ability--whereas the environment

contributes to differences in performance.

These conclusions have far-reaching implications for

education and child development as well as for molecular

genetics and neuroscience.