Just thinking you have poor endurance genes changes your body

If you want to win a race or stick to a difficult diet, coaches of all kinds will tell you it’s all about “mind over matter.” But that advice rarely crosses over into the medical community, where an inborn ability—or risk—is thought to depend more on genes and environment than on mindset. Now, in a study examining what may be a novel form of the placebo response, psychologists have found that just telling a person they have a high or low genetic risk for certain physical traits can influence how their body functions when exercising or eating, regardless of what genetic variant they actually have.

The results could be an eye-opener for medical providers and consumer DNA testing companies. “From a psychological science perspective, it’s not terribly surprising that genetic risk information can function this way,” says behavioral researcher Susan Persky of the National Human Genome Research Institute in Bethesda, Maryland, who was not involved in the study. But it’s a novel idea in the genetics community, she adds.

After getting ethics approval to conduct an experiment that involved deceiving...