WASHINGTON (AFP) - Want to make a bet? The answer probably lies in your genes.

Researchers said on Monday that a study of more than 200 people has shown that genetics plays a big role in how a person acts when it comes to betting and investing.

The genes in question affect the role of dopamine, a chemical released in the brain that signals pleasure and motivates people to seek rewards.

Dopamine is already known to play a role in social interactions, but researchers at the University of California, Berkeley, said their study is the first to show how genes govern the way dopamine functions in the brain.

"This study shows that genes influence complex social behavior, in this case strategic behaviour," said lead study author Ming Hsu, an assistant professor of marketing in UC Berkeley's Haas School of Business.

The research involved 217 undergraduates at the National University of Singapore. Their genomes were scanned for some 700,000 genetic variants.

Then, researchers focused on certain variants within 12 genes involved in regulating dopamine.

They studied the students' brains with MRI imaging as they engaged in a competitive game, in which one person bet via computer with an anonymous opponent.

Those who were better at being able to imagine their competitor's thinking and anticipate and respond to the actions of others had a variation in three genes that affect how dopamine functions in a certain part of the brain, known as the medial prefrontal cortex.

Those who were better at trial-and-error learning had a variation in two genes that primarily affect dopamine in the brain's striatal region.

Researchers found that the genetic role in decision-making was evident with a "surprising degree of consistency" among those studied.

"Our results add to growing evidence that dopamine mechanisms critically underlie a wide class of value-based decision-making across both social and nonsocial settings," said the study, published in the Proceedings of the National Academy of Sciences.