Math and reading skills were shown to have a shared genetic basis according to a twin study report. 12-year-old twins, 2,800 in total, that were enrolled in the Twins Early Development Study participated in math and reading skills testing using both web-based and phone-based tests. The twin sets were both identical and non-identical. They also provided DNA samples for genetic testing. The results showed that there was a substantial genetic component associated with reading and math scores. An additional finding suggested that probably about half of the genetic variants affected both math and reading skill traits, which means that the scores were associated by a shared genetic basis.
The study was carried out in the United Kingdom and reported in Nature Communications. The funding for the study came from the Wellcome Trust Case Control Consortium 2 project and a grant from the UK Medical Research Council. Dr. Oliver Davis was the lead scientist directing the study.
There has been long standing interest in determining the role that genes and the environment play in intelligence. The famous nature versus nurture question was studied and argued about for decades before there was realization that both must play a role. It is not possible for genes to be at work without an environment, at all levels, and the environment cannot have an effect on an organism without the genes being at work in the organism. Synthesis of nature and nurture has been found to be the answer to this famous question. How much genes contribute to traits such as intelligence is still an interesting quest for many. Given the developments in genetic analysis technology that has occurred in the last two decades, it is inevitable that these new methods would be applied to the question of genetic contributions to intelligence.
One of the tools used in this study was a genome-wide association study (GWAS). This is a very large-scale type of study in which DNA samples are obtained from a large number of individuals, usually by having them spit saliva into a tube, and then the entire genome of each individual is searched through to identify single-nucleotide polymorphisms (SNPs) that are then analyzed en masse by complicated algorithms using computer software programs. The results from a GWAS indicate which SNPs, from thousands that may be studied, show a statistically significant association with a chosen trait, such as math and reading skills. A GWAS is like searching for a needle in a haystack because a great deal of DNA information from many people is analyzed to identify very small snippets of DNA sequence.
The authors of the study on the 12-year-old twins stated that the two traits, that is, math and reading skills, are pleiotropic. Pleiotropic means that one gene, or a few SNPs, affect unrelated traits. It means that the genetic basis for what are seemingly unrelated traits is the same. Reading and solving mathematical problems are seen to be very different types of mental tasks and could be considered unrelated traits. The study on twins suggested that how well one does on these very different types of mental tasks may come from a common genetic basis. Math and reading skills seem to come from a similar genetic basis.
By Margaret Lutze