LONDON, Oct 11: The high heritability of exam grades reflects many genetically influenced traits such as personality, behaviour problems and self-efficacy and not just intelligence, a new study has found.
The study led by King’s College London looked at 13,306 twins at age 16 who were part of the Medical Research Council (MRC) funded UK Twins Early Development Study (TEDS).
The twins were assessed on a range of cognitive and non-cognitive measures, and the researchers had access to their GCSE (General Certificate of Secondary Education) scores.
In total, 83 scales were condensed into nine domains: intelligence, self-efficacy (confidence in one’s own academic ability), personality, well-being, home environment, school environment, health, parent-reported behaviour problems and child reported behaviour problems.
Identical twins share 100 per cent of their genes, and non-identical twins (just as any other siblings) share 50 per cent of the genes that vary between people. Twin pairs share the same environment (family, schools, teachers etc).
By comparing identical and non-identical twins, the researchers were able to estimate the relative contributions of genetic and environmental factors.
So, if overall, identical twins are more similar on a particular trait than non-identical twins, the differences between the two groups are due to genetics, rather than environment.
“Previous work has already established that educational achievement is heritable. In this study, we wanted to find out why that is,” Eva Krapohl, joint first author of the study, from the Institute of Psychiatry, Psychology & Neuroscience (IoPPN) at King’s, said.
“What our study shows is that the heritability of educational achievement is much more than just intelligence – it is the combination of many traits which are all heritable to different extents.
“It is important to point out that heritability does not mean that anything is set in stone. It simply means that children differ in how easy and enjoyable they find learning and that much of these differences are influenced by genetics,” said Krapohl.
The researchers found that the heritability of GCSE scores was 62 per cent. Individual traits were between 35 per cent and 58 per cent heritable, with intelligence being the most highly heritable. Together, the nine domains accounted for 75 per cent of the heritability of GCSE scores.
The study was published in the journal PNAS. (PTI)
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