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Surprising Science

How Genetic Is Intelligence?

Some recently unearthed data sets allowed scientists to examine how genetics affect cognitive decline as part of the aging process. Genes are influential but not determinative.

What’s the Latest Development?

A pair of previously confidential data sets out of Scotland have allowed scientists to examine the role genetics play in cognitive decline as part of the aging process. The data comes from a survey taken of thousands Scottish 11-year-olds in 1932 and 1947. After the data was uncovered in the 1990s, English scientists tracked down about 2,000 of the original participants, collecting DNA samples and performing fresh intelligence tests. They found that childhood intelligence correlates with intelligence in old age, but why?

What’s the Big Idea?

Using the DNA samples, scientists tested for the presence of more than half a million common genetic variants, calculating whether these variants were associated with cognitive stability and how well intelligence had been maintained over time. The conclusion reached is that as people age, genetic predisposition accounts for about the quarter of the changes that affect cognitive ability. While that still leaves plenty of room for environmental factors, scientists hope to find genetic markers for degenerative diseases like Alzheimer’s.

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