Why is educational achievement heritable?

Posted on 7 October 2014

New research involving the University of York has found that the high heritability of exam grades reflects many genetically influenced traits such as personality, behaviour problems and self-efficacy, and not just intelligence.

The study, published in the Proceedings of the National Academy of Sciences (PNAS), 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.

Dr Kathryn Asbury, from York’s Education Department’s Psychology in Education Research Centre and one of the report authors, said: “This research makes crystal clear why there will never be a gene ‘for’ achievement. How well young people perform in their GCSEs is bound up with their home lives, their school lives, their personalities and their health and well-being, as well as their cognitive abilities. Understanding the genetic and environmental relationships between this broad array of pupils’ experiences and behaviour and their GCSE performance may eventually help us to personalise teaching and learning more effectively than we currently do.”

The study was led by Eva Krapohl and Kaili Rimfeld, from the Institute of Psychiatry, Psychology & Neuroscience at King’s College London. Eva Krapohl said: “Previous work has already established that educational achievement is heritable. In this study, we wanted to find out why that is. 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.”

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.

Heritability is a population statistic which does not provide any information at an individual level. It describes the extent to which differences between children can be ascribed to DNA differences, on average, in a particular population at a particular time.

Kaili Rimfeld, from King’s College London, said: “No policy implications necessarily follow from finding that genetics differences influence educational achievement, because policy depends on values and knowledge. However, our findings support the idea that a more personalised approach to learning may be more successful than a one size fits all approach. Finding that educational achievement is heritable certainly does not mean that teachers, parents or schools are not important. Education is more than what happens to a child passively; children are active participants in selecting, modifying, and creating their experiences – much of which is linked to their genetic propensities, known in genetics as genotype–environment correlation.”

TEDS is supported by the UK Medical Research Council with additional funding from the National Institutes of Health.

Further information:

The article “The high heritability of educational achievement reflects many genetically influenced traits, not just intelligence” by Krapohl, E. et al is published in Proceedings of the National Academy of Sciences (PNAS).
More information on the UK Twins Early Development Study (TEDS) at http://www.teds.ac.uk/
More information on the University of York’s Department of Education at www.york.ac.uk/education