The largest-ever genetics study in the social sciences has turned up dozens of DNA markers that are linked to the number of years of formal education an individual completes. The work, reported this week in Nature, analysed genetic material from around 300,000 people.
“This is good news,” says Stephen Hsu, a theoretical physicist at Michigan State University in East Lansing, who studies the genetics of intelligence. “It shows that if you have enough statistical power you can find genetic variants that are associated with cognitive ability.”
Yet the study’s authors estimate that the 74 genetic markers they uncovered comprise just 0.43% of the total genetic contribution to educational achievement (A. Okbay et al. Nature http://dx.doi.org/10.1038/nature17671; 2016). By themselves, the markers cannot predict a person’s performance at school. And because the work examined only people of European ancestry, it is unclear whether the results apply to those with roots in other regions, such as Africa or Asia.
The findings have proved divisive. Some researchers hope that the work will aid studies of biology, medicine and social policy, but others say that the emphasis on genetics obscures factors that have a much larger impact on individual attainment, such as health, parenting and quality of schooling.
“Policymakers and funders should pull the plug on this sort of work,” said anthropologist Anne Buchanan and genetic anthropologist Kenneth Weiss at Pennsylvania State University in University Park in a statement to Nature. “We gain little that is useful in our understanding of this sort of trait by a massively large genetic approach in normal individuals.”
The study is the latest to apply genetic analysis to social science. Some of its authors have also studied the genetics of happiness, and plan to examine the genetics of fertility and of risk-taking behaviour.
“There’s been a long-standing assumption that [genetic] differences among people are not really relevant for social-science studies,” says study co-author Christopher Chabris, a cognitive psychologist at Union College in Schenectady, New York. “The main effect of this work may be the increasing realization that genetic differences matter, and now people can start to figure out how and why.”
Robert Plomin, a behavioural geneticist at King’s College London, agrees. The study’s authors identified 9 million genetic variants that, as a group, have some influence on school success; these include the 74 genetic markers that show strong individual influence. Considered as part of an overall ‘polygenic’ score, the variants explain 3.2% of the differences in educational attainment between individuals. Plomin says that such studies could pave the way to predictive genetics for traits such as how well children perform on standardized tests.
Still, the researchers estimate that a person who carries two copies of the genetic variant that has the strongest known effect would complete nine more weeks of schooling over a lifetime than a person with no copies.
The authors also report that the markers they found overlap with those associated with better performance in cognitive tests, bolstering the idea that educational attainment is a proxy for intelligence. Because few large studies have tested individuals’ cognitive performance, it has been difficult to discern genetic factors linked to intelligence. But it is much easier to amass large amounts of data that have sufficient statistical power to uncover genetic effects related to educational attainment, because medical studies routinely record data on participants’ years of schooling.
Hsu predicts that growing knowledge of genetic contributions to intelligence could be used to help parents to select embryos created through in vitro fertilization.“You could allow the parents to decide whether they want to implant or not implant an embryo that has a serious cognitive impairment,” Hsu says. “What is missing is the ability to know what places in the genome are affecting cognitive ability, but studies like this one will get us to that point.”
But even if all the genetic contributors to educational attainment were known, the study’s authors say, their effect would probably be overshadowed by other factors such as the socio-economic and educational status of a child’s family. Says Chabris, “It would be irresponsible to look at a polygenic score and use it to make a prediction for a single individual”.
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