OMG, There's a Credit Card Gene

There are some genetics discoveries that make me sit up straight, reread to make sure I understand what the scientists have found, and then think to myself, this cannot end well. I'll cut to the chase: genetic testing as part of your credit-card or mortgage application? (Click here to follow Sharon Begley)

The discovery in question is that people who carry a particular variant of a well-studied gene are more likely—significantly more likely—to rack up credit-card debt. In a world where decisions about loans take into account whether you drive a hybrid (you're conscientious!), whether you have unpaid medical bills (bad, irresponsible person), and whether you installed solar panels on your roof (ample disposable income, and thus more likely to pay back the loan), it doesn't seem too far-fetched that genotype will be the next thing that will be factored into the complex algorithms that are used for credit scoring.

The gene is monoamine oxidase A, or MAO-A to its friends. What it does is make an enzyme that (among other functions) breaks down the brain chemicals serotonin and dopamine. MAO-A comes in two forms, one with high activity and efficiency (allowing it to break down the neurotransmitters more quickly) and the other with low activity and efficiency. MAO-A's effect on neurotransmitters means that it should also have an effect on the brain and thus on behavior, and hundreds of earlier studies have found that it does. MAO-A has been linked to antisocial and criminal behavior in adolescents, to the risk of developing major depression, to vulnerability to such environmental stressors as abusive treatment in childhood, to impulsivity, and to aggression following provocation. (That last association is why MAO-A has been dubbed "the warrior gene.")

In the new study (my thanks to the Neuroethics & Law Blog and The Future Now blog for noticing the paper), graduate student Jan-Emmanuel De Neve of the London School of Economics & Political Science and James Fowler of the University of California, San Diego, report that young adults age 18 to 26 with the low-activity form of MAO-A are more likely to have credit-card debt. Because everyone has two copies of the MAO-A gene (one from mom and one from dad), a person can have two low-efficiency forms, or alleles, two high-efficiency alleles, or one of each. The authors find that "having one or both MAO-A alleles of the low-efficiency type raises the average likelihood of having credit card debt by 7.8% and 15.9% respectively."

That's not huge, obviously. And the authors do not distinguish between carrying credit-card debt and skipping out on that debt (don't card issuers prefer us to carry a balance, the better to rake in interest payments?). About half the U.S. population has at least one low-efficiency MAO-A gene. In principle, a financial institution assessing an applicant's credit risk could therefore factor in MAO-A status, viewing it favorably if they're looking for credit-card users who will carry a balance and thus be on the hook for nice fat interest payments, or seeing it as a black mark if they want to keep mortages out of the hands of people who might in the future carry a debt load.

Yeah, yeah, I hear the objections now. The study identifies a correlation, not a cause. True. Also, genes are not deterministic, traits (especially complex ones such as behavior) emerge from complicated interactions between our DNA and our experiences, blah blah. Tell that to the companies that set car-insurance rates based in part on age, sex, and marital status: being young, male, and single isn't deterministic for crashing your car either, but that doesn't stop insurers from factoring it in to what they charge you. Is it so far-fetched that DNA will become such a factor, too?

Oh, and did I mention that it's possible to extract DNA from the remnants of saliva on stamps and envelope flaps? No need to actually send the mortgage company or credit-card issuer a cheek swab!

As I said, this cannot end well.