No stomach for the ups and downs of the financial market? Or maybe you lost everything in the global economic downturn? Genes important for mood and risk-taking likely played a clear role, U.S. researchers reported on Tuesday.

They found surprisingly clear-cut links between two genes and the willingness of people to gamble with money.

The study, published in the Public Library of Science journal PLoS ONE, supports others that point to brain chemicals and their roles in financial risk-taking.

The genes involve dopamine, a brain chemical known as a neurotransmitter linked with movement and risk-taking, and serotonin, a neurotransmitter important in controlling mood.

People with the “high-risk” version of the dopamine gene tended to invest in risky but potentially lucrative propositions, while those with the “high anxiety” version of serotonin managed their money more carefully, Camelia Kuhnen and Joan Chiao of Northwestern University in Chicago reported.

“We had people come to the lab. We gave them money and asked them to invest the money as they wanted,” Kuhnen said in a telephone interview.

“They could split the money between a risky asset and a safe asset like a savings account.”

The 60 volunteers, mostly students, also gave saliva samples for a DNA test. Kuhnen and Chiao had a commercial genetic lab test the samples for variations on the two genes known to be associated with dopamine and serotonin levels, and suspected of being involved in risk-taking behavior.

About a third of the volunteers had the high-risk profile, and another third had the high-anxiety profile. Although two different genes were involved, the two types did not overlap in this group, Kuhnen said.

People with the “anxious” version of the serotonin transporter gene 5-HTTLPR invested 28 percent less money in risky investments than people with the non-anxious version.

People with the high risk-taking version of the dopamine gene DRD4 invested about 25 percent more in risky investments than those with the more common version, the researchers said.

“As we sort through the devastating consequences of this financial crisis, it might be useful to note how our genetic heritage is influencing our economic behavior,” Chiao said in a statement. “Think about how the excessive risks taken by just a few affected so many, from large institutions to average people.”

Kuhnen noted that many other studies have suggested that risk-taking behavior is influenced far more by experience than by genes. “People may learn a lot from this crisis,” she said.

WASHINGTON (Reuters)