Overspending: Blame It on Your Debt Gene?

When you apply for a mortgage in 10 years, you may be asked for your bank statements, your pay stubs… and a cheek swab. At least that’s one possible implication of a new study, which reports a groundbreaking finding: that whether you carry a specific gene variant can predict your propensity to rack up credit-card debt.

Specifically, Jan-Emmanuel De Neve, of the London School of Economics, and James Fowler, of the University of California, San Diego, have found that if you carry one or both “low efficiency” alleles of the MAOA gene — we’ll get to what exactly the MAOA gene is and does in a minute — the likelihood that you have credit card debt increases by 8% and 16%, respectively.

It’s a first-of-its-kind result, but what exactly does it mean? Does it mean that humans carry a “debt gene”? And if you were to carry such a gene, does that mean you’re doomed to a life of financial turbulence and tribulation?

To begin to answer these questions, one must understand the complex relationship between genes and behavior. Unlike with physical characteristics (such as eye color), behavioral traits (such as violence or impulsivity) are tricky to identify and arise from a tremendously complex interplay of brain systems and environment.

The heritability of human behavior has been studied systematically since the 19th century. Traditionally, it’s been studied using twins and adoptees, to tell us how much of a trait is explainable purely by genetics, as opposed to environmental or other influences. And that approach has been extremely fruitful. Recent twin studies, for instance, have shown us that some surprising things have major genetic components: risk-taking, the tendency to cooperate, happiness levels, political preferences — even whether or not a person is likely to turn out to vote, donate to a political candidate, or run for office him or herself.

The rising availability of DNA analyses, however, is now making it possible for scientists to try to link specific genes to specific behaviors.

So, is there a “debt gene”?

“There will never, ever be such a thing as a ‘debt gene’,” says De Neve. But what humans likely have is “a set of genes whose expression, in combination with environmental factors, influences financial decision-making.”

The MAOA gene appears to be one of these genes.