The research, published in the journal Nature Genetics, is one of the largest genetics studies to date. It is based on genetic information from over one million individuals with European ancestries - more than three times the size of the 2016 study.
Scientists have identified nearly 1,300 genetic variants associated with how much education someone may complete - far more than the 74 variants initially discovered in a smaller study two years ago.
The research, published in the journal Nature Genetics, is one of the largest genetics studies to date. It is based on genetic information from over one million individuals with European ancestries - more than three times the size of the 2016 study.
The total influence of the genetic variants is small, explaining about four per cent of the variation in educational attainment across individuals, the scientists said.
They found that genetic variants on the X chromosome explain virtually identical amounts of variation in men and women.
This finding lends support to the hypothesis that there are no genetically based sex differences in the amount of variation in educational attainment, the researchers said.
"Even variants with the largest effects predict, on average, only about three more weeks of schooling in those who have those variants compared to those who don't," said Daniel Benjamin, an associate professor at the University of Southern California (USC) in the US.
"Yet when we analyse the combined effects of many genetic variants, taken together they can predict the length of a person's formal education as well as demographic factors," Benjamin said.
Scientists have known for many years that demographic factors are associated with educational attainment, including household income and maternal education.
To assess the importance of the gene variants in educational attainment, the scientists established a "polygenic score" that captures the predictive power of a combined one million genetic variants - including those specifically linked to educational attainment and the other remaining variants that the scientists had measured across the genome.
The scientists found that the predictive power of the score is as large as that of demographic factors.
"The very small effects of individual genetic variants confirms what we have seen in our earlier work, and it's an important finding in itself," Benjamin said.
"It would be completely misleading to characterise our results as identifying 'genes for education.' Yet the polygenic score is useful for research because it combines the effects of a very large number of genetic variants," he said.
For the latest study, the scientists analysed a combined 71 data sets comprising over 1.1 million participants with European ancestry from 15 different countries and who were at least 30 years old.
Educational attainment is primarily influenced by environmental and social factors, but it is also influenced by genes associated with, for example, cognitive function such as memory and personality traits such as conscientiousness.
"We found that many of the genes associated with educational attainment are influential in virtually all stages of brain development and in neural communication within the brain, said Peter Visscher, a professor at the University of Queensland in Australia.
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