My Alleles Made Me Do It: The Folly of Blaming Bad Behavior on Wonky DNA

Blame your genes? That’s a good way to salve your conscience if you develop melanoma, hypertension, or colon cancer. Although the risk of all of these diseases is greater if you get sunburned, or fail to exercise and eat a healthy diet, respectively, they also have a genetic component. And guess which is easier to live with: the idea that your behavior landed you in the cancer ward or the cardiac ICU, or the idea that your illness is beyond your control? A new study shows just how alluring “My DNA did it!” is to some people.

Although scientists may try to be nuanced when they sing the praises of DNA testing to alert people to the diseases they are at risk for, the business model of personal-genome companies such as 23and me, Navigenics, and Pathway Genomics requires that people believe the genes they inherited from Mom and Dad have a strong influence on their health. As the Web sites of two of the companies proclaim, “Take charge of your health,” and “The smart way to look at your health.” That is probably a large reason why so many Americans say they would like to know their DNA profile, as NEWSWEEK's Claudia Kalb reported.

But there are serious scientific concerns about the reliability and value of many of the genes linked to disease. And now we have another reason why the hype is worrisome: people who engage in the riskiest-for-health behaviors, and who therefore most need to change, are more likely to blame their genes for their diseases, finds a new study published online in the journal Annals of Behavioral Medicine. Worse, the more behavioral risk factors people have—smoking and eating a high-fat diet and not exercising, for instance—the less likely they are to be interested in information about living healthier.

Overall, the 1,959 healthy adults (ages 25 to 40) who completed the survey asking about their health, their habits, and their beliefs thought the way they lived was the main cause of any health problems they had. They also were more interested in receiving information about healthy behaviors: 67 percent said it was very important to learn about healthy behaviors, vs. 56 percent who said it is very important to learn about genetic risk factors.

But the adults with the least-healthy habits didn’t fit this pattern, found scientists led by Suzanne O’Neill of Georgetown University. The unhealthier people’s habits were, the more they latched on to genetic explanations for diseases (in particular, colon cancer, skin cancer, hypertension, and lung cancer). “Those most at risk are often the most likely to downplay and distance themselves from threatening health information,” the scientists conclude.

They suspect that this was a defensive reaction, in which people knew at some level that they were engaging in behaviors likely to lead to illness down the road (remember, these were all healthy adults at the time of the survey) but wanted to blame potential health problems on factors beyond their control. In the study, 25 percent of the participants were smokers, another 25 percent were not physically active five days a week, and 36 percent had a body-mass index above 30. If you think your plaque-clogged arteries, uncontrolled diabetes, or lung cancer will be caused by genes in the fertilized egg that became you—rather than your junk-food diet and two-pack-a-day habit—it absolves you of blame.

That’s bad enough. But people with the least-healthy habits were also least interested in learning about ways to live healthier. If DNA is destiny, they apparently figured, why bother learning about healthy alternatives to doughnuts for breakfast, Big Macs for lunch, and three hours of evening TV? Blaming DNA—a message we are hearing more and more as personal genomics spreads—bodes ill for efforts to get people to adopt healthier habits.