Do you squander all your dough at the casino? Maybe it's because your DNA is telling you to take risks with your money.

OK, it's not as simplistic as that. But Northwestern University researchers say they've linked two genes with our tendency to be bold or conservative investors, according to their study set to be published tomorrow in PLoS One. The genes regulate the brain's systems of dopamine and serotonin, chemicals important in areas of the brain that are active when we take or shun risk, respectively.

The findings were based on 65 people (two-thirds women, one-third men) who answered 96 questions about how they would use $30 in real money in a computerized investment game. The participants each provided a saliva sample so that researchers could genotype their DNA.

The scientists discovered that participants with two short versions of the 5HTTLPR gene, which regulates serotonin, invested 28 percent less of their money in a risky (but potentially more profitable) fund than did people with other gene combos. Similarly, those with a long version of the DRD4 gene, which regulates dopamine, invested 25 percent more of their money in the risky fund than those with other variations of that gene.

Deficiencies of serotonin, which regulates moods, have been linked to anxiety and depression. Dopamine, a chemical central to the brain's reward system, is associated with drug, gambling and other addictions. Scientists are increasingly studying the potential effect of genes and the brain on financial decision-making, a field called neuroeconomics.

Before you ask your financial advisor for a saliva sample, though, bear in mind that only about 20 percent of the difference in risk-taking is due to genes, says study co-author Camelia Kuhnen, an assistant professor of finance at Northwestern's Kellogg School of Management. "I wouldn’t want to oversell this as a screening device to find good traders," Kuhnen tells ScientificAmerican.com. "Even if I have a gene that predisposes me to taking a lot of financial risk, I could go through a stock market crash that will make me less risk-taking."

Previous research has suggested that high levels of testosterone are linked with more financial risk-taking. Kuhnen said there wasn’t a difference in the distribution of the serotonin and dopamine genes between the study's men and women, and added that it's unknown whether the genes' link with financial risk-taking is as strong in the real world, where the stakes are much higher. "Even after we replicate these findings," Kuhnen says, "I still don’t know if it would be ethical to have screening criteria based on the genetic markers of individuals, because most behavior is driven by things that are not genetic."

Image © iStockphoto/Tomislav Forgo