Diagnostic labels such as dyslexia and dyscalculia tend to highlight the separateness of various mental capabilities from general intelligence. But a new study has shown that most of the genes that influence young children’s mathematics ability also influence their reading and general intelligence. According to Robert Plomin and colleagues at the Social, Genetic and Developmental Psychiatry Centre at King’s College in London, this is probably because “a great variety of non-specific abilities, such as long-term memory, working memory and attention are involved in mathematical ability as well as in reading and general intelligence”. They made their finding by testing thousands of twins, some identical with matching genes, and others non-identical, who share half each other’s genes. The twins’ mathematics ability was assessed at seven years of age via teacher reports, and their reading and general intelligence was tested over the phone.
Plomin’s team found two thirds of the genetic influence on maths ability also explained variation in reading and general intelligence, thus suggesting most of the genes that affect maths also affect reading and general intelligence. Whereas genes tended to explain the similarity of a child’s performance across these domains, environmental factors tended to explain the differences. “One direction for future research is to identify the non-shared environmental factors that are experienced differently by twins, even identical twins, even in the same classroom and that contribute to differences in children’s relative performances in mathematics and reading”, the authors said.
Non-shared environmental factors are experiences that have uniquely affected one twin but not the other, even though they have been raised and taught together. Lead researcher Yulias Kovas told The Digest such factors could include “…pre-, peri- and post-natal influences, including childhood illnesses, differential parental influence, or differential effects of curricula on children”. Kovas added that “If these non-shared environmental factors can be identified, they could lead to more individualized curricula, although much more research is necessary to clarify whether such a move towards individualization in education is necessary or practically possible”.
Kovas, Y., Harlaar. N., Petrill, S.A. & Plomin, R. (2005). ‘Generalist genes’ and mathematics in 7-year-old twins. Intelligence, 33, 474-489.
Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.