The technique is the strongest prediction of behaviour from DNA to date, researchers said.
The research shows that a genetic score comprising 20,000 DNA variants explains almost 10 per cent of the differences between children’s educational attainment at the age of 16.
The findings from King’s College London mark a ‘tipping point’ in predicting academic achievement and may help identify children who are at greater risk of having learning difficulties.
Twin studies can tell us the overall genetic influence on a trait in a population. Polygenic scores, however, estimate genetic influence from common variants only, which explains the discrepancy between these DNA-based studies and twin studies (10 per cent vs 60 per cent).
As human traits are so complex and influenced by thousands of gene variants of very small effect, it is useful to consider the joint effects of all of these trait-associated variants – and this principle underlies the polygenic score method.
Calculating an individual’s polygenic score requires information from a genome-wide association study (GWAS) that finds specific genetic variants linked to particular traits, in this case academic achievement.
Some of these genetic variants, known as single nucleotide polymorphisms (SNPs), are more strongly associated with the trait, and some are less strongly associated.
In a polygenic score, the effects of these SNPs are weighed by the strength of association and then summed to a score, so that people with many SNPs related to academic achievement will have a higher polygenic score and higher academic achievement, whereas people with fewer associated SNPs will have a lower score and lower levels of academic achievement.
The new research examined almost 10 million SNPs and identified 74 genetic variants that were significantly associated with years of completed education.
‘Years of education’ was used as a proxy measure for education achievement and related traits.
Researchers measured academic achievement in Mathematics and English at ages 7, 12 and 16, in a sample of 5,825 individuals from the Twins Early Development Study (TEDS).
Their findings show that what makes students achieve differently in their educational achievement is strongly affected by DNA differences.
On average those with a higher polygenic score would obtain a grade between A and B, while those with lower score obtained an entire grade below at age 16.
About 65 per cent of people in the higher polygenic group went on to do A-levels, whereas only 35 per cent from the lower group did so.
The findings appear in the journal Molecular Psychiatry.
PTI