The Brain

Genes are not destiny: environment and education still matter when it comes to intelligence

The ConversationRecent research has suggested that academic performance, reading ability and IQ have a genetic basis. This reinforces the popular notion that intelligence and related cognitive capacities are somehow “in our genes”.

This has led some people to reject the importance of educational interventions on the grounds that spending money on nurture isn’t going to significantly affect the abilities nature has given us.

However, genes are not destiny. There is good evidence to show how effective environmental interventions can be for educational outcomes.

Genetics and intelligence

The way in which genes actually contribute to intelligent individuals is often overlooked.

Genes can act in a variety of ways to produce their effects. Some genes may alter brain chemistry so that a person is better able to learn. Other genes could cause behavioural differences, causing some people to self-select more stimulating environments.

And it is likely that the genetics of intelligence works at least in part by a genetic influence on the environment. This means that a genetic basis for intelligence is as much about one’s nurture as about one’s nature.

Intelligence is the most widely studied trait in behavioural genetics. It is correlated with a suite of other characteristics ranging from income, to lifespan, to happiness.

Researchers have found a significant genetic contribution to intelligence differences using the method of heritability estimates.

Born clever? DONOT6_STUDIO/Shutterstock

These studies compare populations of identical (monozygotic) and fraternal (dizygotic) twins. Identical twins are genetically identical – they’re nature’s clones. Fraternal twins, like siblings, share an average of 50% of their genes.

If there is a heritable basis for intelligence, then identical twins should be more similar than fraternal twin pairs. This method gives researchers an idea of how heritable intelligence is, but tells us nothing about the actual genes involved.

Since the advent of gene sequencing, new techniques have allowed scientists to identify specific candidate genes that are correlated with intellectual outcomes.

More recently, researchers have investigated the relative effects of many specific genes working together. Earlier this year researchers at Kings College London used this method to explain a substantial proportion of exam score differences.

The standard interpretation of these kinds of results is that intelligence genes work through innate biological processes, causing individual differences. But this may not always be the case.

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