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The genetics of risky behaviour

124 genetic variants associated with risk tolerance
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EUNICE CHEN/THE VARSITY
EUNICE CHEN/THE VARSITY

According to a recent study published in Nature Genetics, risky behaviour may be linked to genetics. The international collaborative project involved 96 co-authors and identified 124 independent genetic mutations associated with general risk tolerance in humans. 

Risk tolerance refers to a person’s willingness to take a risk, with the goal of attaining a reward. “People who have higher risk tolerance are more likely to start up their own business, to invest in risky stocks, to do risky sports, take social risks and so on,” said Dr. Jonathan Beauchamp, one of the senior principal investigators and Assistant Professor of Economics at U of T, at the 2018 Paul G. Allen Frontier Group Conference. 

Risk tolerance “is such a fundamental parameter in the behavioural sciences,” continued Beauchamp. “It’s really at the core of all the economic models, macroeconomics, and also labour market decisions.”

The findings of this study provide examples of the many insights that can be gained from genome-wide association studies, which scan the genomes of many people in an attempt to associate genetic variants with particular outcomes. 

Genetic information and self-reported answers to questions regarding risk tolerance were collected from 12 different genetic databases, including UK Biobank and 23andMe. The study involved over one million people of European ancestry.

Once the researchers completed the data collection, genetic variants were matched with their respective risk tolerance profiles, and associations were made between various behaviours.

The 124 identified genetic variants play a small role in influencing risk tolerance when assessed individually. But together, the associations can help explain the genetic basis of risky behaviour. 

When the effects from all 124 variants were combined, a polygenic score, or numerical value that accounts for all variants in a single distinct genome, was created.

The polygenic score can explain up to about 1.6 per cent of variation in risk tolerance across a population. While this score does not have predictive value to determine the risk tolerance of a certain individual, it can be put to use in social science studies, which focus on the behaviour of a population.

The study also points to the high genetic association between risk preferences and risky behaviours. 

“There’s a debate in economics as to whether there is domain-general or domain-specific risk preferences, meaning whether your risk preference for health is correlated to your risk tolerance for driving fast or investing and so on,” said Beauchamp. “Some people have concluded that it seems they’re not correlated… but we find that, at the genetic level, there really seems to be a genetic component that affects risk preferences across domains.” 

The researchers found no support for the involvement of the main biochemical pathways previously thought to be related to risk tolerance, which included dopamine, serotonin, cortisol, estrogen, and testosterone. 

Instead, they found a role for the main excitatory and inhibitory neurotransmitters in genetically determined risk tolerance, glutamate and GABA respectively.

Beauchamp explained that this lack of corroboration is likely due to the relatively small sample sizes of previous studies. 

“To date… nearly all published studies attempting to discover the genetic variants associated with risk tolerance have been ‘candidate-gene studies’ conducted in relatively small samples ranging from a few hundred to a few thousand individuals.” 

As a result, the sample sizes from the candidate-gene studies were too small to identify genetic variants involved in risk-tolerance.

In part, this issue fostered Beauchamp’s support and involvement in the Social Science Genetic Association Consortium, which pools samples of genetic information so that researchers can look into genetic links using large sample sizes.

However, with all the media hype around genetics, Beauchamp warned not to neglect ‘nurture’ when it comes to human behaviour. 

“I think it’s important to emphasize that environment also matters, so we’re not saying that genes are the only thing important for risk,” said Beauchamp.