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Genetics the cause of variations in intelligence?

10 August 2011

If you battle with books, struggle with sums or get confused by crosswords, who should you blame - your teachers or your parents?



Well, according to a new study part-funded by Age Scotland and published online by the journal Molecular Psychiatry, you really should blame both.

The Edinburgh University study's findings indicate that the genes someone is born with do play a important role, but are only part of the story.

After examining the blood of more than 3,500 people from Aberdeen, Edinburgh, Newcastle and Manchester for tiny changes in their DNA, researchers found that 40% of the variation in knowledge could be explained by DNA differences.

So-called fluid-type intelligence, the ability to reason and think abstractly under pressure, was governed by genetics to an even greater extent. Some 51 per cent of a person's ability to ‘think outside the box' is down to DNA.

The study is the first to find a genetic contribution by testing people's DNA for up to half a million genetic markers or minute variations, but the researchers do not yet know which genes are the most important in determining intelligence.

Professor Ian Deary, one of the research leaders, said: "We are studying genetics to find out how things work, and these new findings tell us that individual differences in intelligence are strongly associated with many important life outcomes, including educational and occupational attainments, income, health and lifespan."

Professor Deary, who hopes to unlock the secrets of those whose brains age well, with a view to helping others stay sharp as they get older continued: "The study's results unequivocally confirm that a substantial proportion of individual differences in human intelligence is due to genetic variation. If we can find specific genetic contributions to people's experience of cognitive ageing, this can suggest the mechanisms by which people differ."

The research was co-ordinated in Edinburgh University's Centre for Cognitive Ageing, home of the project "The Disconnected Mind", which aims to reveal how thinking skills change with age and identify the significance of the brain's white matter during the ageing process.

Professor Deary concluded by saying that those dealt a poor hereditary hand should not act as if their fate is sealed, as it is possible for people to overcome their intellectual inheritance.