If the TV ads are at all effective, plenty of people will be getting the gift of their genetic tests this Christmas. These tests frequently allow people to explore their inherited tendencies toward health problems and, in some cases, may suggest lifestyle changes to ward off future problems—although studies have indicated that few people do.
However, DNA test results can also cause issues that wouldn’t otherwise be there. Genetic information can exert a potent placebo effect—or the opposite, the nocebo effect, wherein if you think that something can harm you, it in fact does. And the potency of this effect has not been studied until now.
Some psychologists at Stanford wondered if the perception of genetic risk could actually increase people’s risk, independent of their actual genetic risk. In other words, could simply learning that you have a genetic propensity for something elicit physiological changes akin to really having that propensity, regardless of whether you have it? The team designed experiments to find out.