DNA ‘shows intelligence variation’

Genetic differences between people could account for up to half the variation in individual intelligence, according to a study.

Researchers at the University of Edinburgh studied two types of intelligence in more than 3,500 people from Edinburgh, Aberdeen, Newcastle and Manchester.

The team found that 40 per cent of the variation in knowledge and 51 per cent of the variation in problem-solving skills between individuals could be explained by DNA differences.

The study examined more than half a million genetic markers on each person and is the first to find a genetic contribution by testing people’s DNA for variations. But the researchers do not know which genes are the most important in determining intelligence.

Ian Deary, professor and one of the research leaders, said: “These new findings tell us that we have found genetic signals associated with people’s intelligence differences.

“We have not found the actual genetic differences that cause some intelligence differences but we now have evidence that some of the genetic causes are linked to those genetic factors that we tested.

“This gives us leads that we are now planning to follow.”

The research, published today in the journal Molecular Psychiatry, was coordinated in the university’s centre for cognitive ageing and was part-funded by the Age UK charity.

Prof. Deary added: “The findings also leave a lot of room for environmental influences and for interactions between people’s genes and their environments. It’s a start to understanding the observed relationship between people’s thinking skills and outcomes in life, and to understanding why some people cognitively age better than others.”