There is no single 'clever gene' – there are thousands, scientists discover

'It should be a great relief that the eugenics possibilities are rather limited because the effects are rather tiny'

Scientists can monitor brain activity but they won't be making our children smarter anytime soon (iStock)

Thousands of genes are involved in intelligence, according to a new study which effectively shatters any hopes of eugenicists that babies can be genetically designed to be clever.

In one of the largest studies of the human genome to date, a group of 253 scientists from around the world identified 74 genetic variants that are associated with the number of years spent in formal education.

Humans’ genetic make-up is believed to be responsible for at least 20 per cent of the difference in educational attainment between individuals, with the rest down to social factors and the environment in which they are raised.

But the researchers found that the largest effect of any one genetic variant was tiny – just 0.035 per cent. This suggests that there must be at least several thousand of genes that are involved.

An Oxford University geneticist asked to comment on the research said it was a “great relief” because it showed there was little chance that people would be able to genetically modify children to be smart.

The researchers, who published a paper in the journal Nature, said that the total effect of the 74 genetic variants on educational attainment was 0.43 per cent.

One of the authors of the paper, Dr Daniel Benjamin, an associate professor at the University of Southern California, said: “The fact that the genetic variant we identify with the largest effect accounts for only 0.035 of one per cent of the variation tells us that there must be at least thousands of genetic variants that influence education but have not yet been detected.”

However he said the “most exciting result” of their research was that they could construct an index of genetic variants from across the genome, called a polygenic score, that could predict about six per cent of the variation.

“That’s not large enough to be useful for predicting any particular individual’s educational attainment, but it’s important because it is large enough to be useful in social science studies, which focus on average behaviour in the population,” Dr Benjamin said.

“For example, we can use the polygenic score to begin to understand how environments magnify or reduce genetic influences on behaviour.

“In fact, in the paper we did some preliminary analysis of how genes and environments interacted in influencing educational attainment.”

Scientists have long realised that a single “gene for” a particular trait does not exist with different genes interacting in complex ways.

Bryan Sykes, professor of human genetics at Oxford University, said he was glad the study had not discovered anything that might be viewed as a gene intelligence.

“I suppose the greatest relief for me is there aren’t really major genes that pop up to correlate very well with educational attainment,” he said.

“If there had been, I’m sure there would have been demands and pressure to select for those.

“It is a great relief, it should be a great relief that the eugenics possibilities are rather limited because the effects are rather tiny.”