Former Harvard president Larry Summers caused a storm in 2005 when he suggested part of the reason women are under-represented in science is because of innate, biological differences between the sexes.
Now, for the first time, researchers in London have looked at the amount of genetic and environmental influence on girls' and boys' science ability. Their finding: nine-year-old girls are just as good at science as nine-year-old boys, and genes and environment affect the science ability of both sexes in just the same way, and to just the same extent.
Claire Haworth and colleagues looked at the science ability (as assessed by teachers) of a sample of 2,602 pairs of 9-year-old twins. Some of the twins were identical, meaning they shared all the same genes; the other twins were non-identical, meaning they shared 50 per cent of their genes, on average, just like non-twin siblings.
The bigger the role played by genes in nine-year-olds' science ability, the more similar (to each other) pairs of identical twins should be in science ability, relative to non-identical twins. And if genes are more important to the science ability of girls than boys, then this difference between identical and non-identical twins, in terms of similarity of science ability, should be greater among female twins than among male twins.
In fact, the researchers found the boys and girls were equally good at science on average, and that genes accounted for about 60 per cent of variation in science ability in both sexes. The remaining variation in science ability was explained, for both sexes, by non-shared features of the environment. These are experiences that have uniquely affected one twin but not the other, even though both siblings have mostly been raised and taught together.
The researchers said their findings “may be useful at a practical level for teachers to recognise that differences among children in their science performance are not just due to differences in effort - genetic sources of differences are also important.”
Moreover, the researchers said that, in the future, specific genes that account for the heritability of science ability may be discovered, thus allowing scientifically weaker children to be helped before problems occur.
Haworth, C.M.A., Dale, P.S. & Plomin, R. (In Press). A twin study into the genetic and environmental influences on academic performance in science in nine-year-old boys and girls. International Journal of Science Education.
Link to related Digest item on enticing more girls into science.
Link to related Digest item on the importance of female role-models.