Asked by: Alex Round, London

Yes. Unpopular as this is, the evidence has always shown high heritability ofIQ, and IQ scores are closely correlated with academic performance, as well as occupation, health and income.

One powerful method compares the abilities of identical and non-identical twins reared together or separately. The most recent conclusion from numerous such studies is that the heritability of intelligence rises from about 20 per cent in infancy to as much as 80 per cent in adulthood. This means that the majority of IQ differences between adults can be attributed to inheritance.

This effect may also be increased by ‘assortative mating’: the tendency of men and women to choose partners who are similar to themselves. Correlations between married couples are greater for intelligence than they are even for personality or height and weight, an effect that increases heritability. Clearly, upbringing, education, friends, health and many other factors influence academic success but genes play a very large part.

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