A brain study has found a gene linked to intelligence, a small piece in the puzzle as to why some people are smarter than others. shutterstock.com

A variant of this gene can tilt the scales in favour of a higher intelligence, study leader Paul Thompson said, stressing though that genetic blessings were not the only factor in brainpower.

Searching for a genetic explanation for brain disease, the scientists stumbled upon a minute variant in a gene called HMGA2 among people who had larger brains and scored higher on standardised IQ tests.

Thompson dubbed it an intelligence gene and said it was likely that many more such genes were yet to be discovered.

The variant occurs on HMGA2 where there is just a single change in the permutation of the four letters of the genetic code.

DNA, the blueprint for life, comprises four basic chemicals called A (for adenine), C (cytosine), T (thymine) and G (guanine), strung together in different combinations along a double helix.

In this case, the researchers found that people with a double C and no T in a specific section of the HMGA2 gene had bigger brains on average.

It is a strange result, you wouldnt think that something as simple as one small change in the genetic code could explain differences in intelligence worldwide, said Thompson, a neurologist at the University of California at Los Angeles.

The discovery came in a study of brain scans and DNA samples from more than 20,000 people from North America, Europe and Australia, of European ancestry.

People who received two Cs from their parents, a quarter of the population, scored on average 1.3 points higher than the next group half of the population with only one C in this section of the gene.

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