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Selective school students differ by genetics and GCSEs

For the first time, researchers from King’s College London have shown genetic differences between students attending selective and non-selective schools. They found that, on average, students attending grammar and private schools had more genetic variants linked to educational success compared to students at non-selective schools. 

The study, published today in the journal npj Science of Learning, also found that the better GCSE results seen in grammar and private schools were almost completely accounted for by factors used to select students, including ability, achievement and socio-economic status.

‘Our study suggests that for educational achievement there appears to be little added benefit from attending selective schools,’ says lead author Emily Smith-Woolley from King’s College London’s Institute of Psychiatry, Psychology & Neuroscience (IoPPN). ‘While schools are crucial for academic achievement, the type of school appears less so.’

Different types of school reportedly set children on different paths to academic success, with selective school students often achieving better GCSE results, getting into better universities and earning more. However, previous research has shown that the factors which selective schools use to choose students are influenced by genetic factors which children inherit from their parents.

To investigate whether selection is linked to any genetic differences between students attending different school types the researchers used data from over 4,000 unrelated students representing UK school populations. The data was taken from the Medical Research Council-funded Twins Early Development Study, and included students’ genotype, family socio-economic status, academic ability and achievement at 11, school type and GCSE results.

Each student’s genetic propensity for educational achievement was measured by a polygenic score. Polygenic scoring looks at how many genetic variants an individual has which are linked to outcomes like educational achievement. There are thousands of genetic variants linked to educational achievement each of which has a miniscule individual effect but when added together can influence a student’s chances of exam success.

The study found that, on average, students in non-selective schools have lower polygenic scores for educational success compared to their peers in selective schools. Three times as many students in the top 10% of polygenic scores went to a selective school compared to the bottom 10%. 

‘Although finding genetic differences between students at different school types may initially seem surprising, when we consider that selection is based on factors which are heritable, the differences are less unexpected,’ says senior author Professor Robert Plomin from IoPPN. ‘School selection results in a system in which children are intentionally phenotypically selected, but unintentionally genetically selected.’

The genetic differences between school types were mirrored in GCSE results, with students at non-selective schools averaging a grade lower across English, maths and science. Initially, school type appeared to explain about 7% of the differences seen in GCSE results. However, after taking into account the selection factors of ability, prior achievement and socio-economic status, school type explained less than 1% of the differences seen in GCSE results, and the average genetic differences between school types were drastically reduced.

‘Although school type appears to have little impact on achievement at GCSE, there are many reasons why parents may opt to send their children to selective schools. Future research is needed to identify if school type makes a difference in other outcomes, such as university and career success,’ says Smith-Woolley.

‘We believe that it is important that teachers, schools and policy-makers start talking about the role of genetics in the classroom, and how to best support each child to help them reach their potential.’


Paper reference

Differences in exam performance between pupils attending selective and non-selective schools mirror the genetic differences between them’, Smith-Woolley et al, npj Science of Learning, DOI: 10.1038/s41539-018-0019-8


For further media information please contact Robin Bisson, Senior Press Officer, Institute of Psychiatry, Psychology & Neuroscience, King’s College London, / +44 20 7848 5377 / +44 7718 697176.