Everyone knows that knowing your genetic profile is supposed to tell you important, influential things about all sorts of aspects of your life and your health. So a paper published this week in Nature Human Behavior explored what happens when that knowledge isn’t true. Researchers tested people for genetic risk factors—one that reduces endurance and one that raises the risk of obesity—and then gave some of them false information about their genetic profiles.
What they found was that people responded, subjectively and physiologically, as if the fake genetic information had been real. People did a treadmill exercise test, then were told they had a bad gene for endurance, then returned to the treadmill. Believing they had that genetic risk not only made them say they felt hotter and that the exercise felt difficult, but it
led to poorer maximum capacity for CO2:O2 gas exchange, decreased the amount of air with which participants supplied their lungs by more than 2 litres per minute, and decreased how long participants ran before giving up during strenuous aerobic exercise compared with their own performance one week earlier when they were naïve to genetic risk.
“All of these changes,” the researchers wrote, “were present regardless of whether the information they had received about genetic risk was true.”
In the other test, people were told they had a gene that protected them from overeating. This information “led them to demonstrate a 2.5-fold increase in physiological satiety and a 1.4-fold increase in self-reported fullness compared with when they consumed the same meal one week earlier.”
Again, their response—including their bodies physically producing a chemical signaling fullness—happened even when the information wasn’t true. In the case of the obesity-risk gene, the effect of a person believing they had the low-risk gene was more powerful than the effect of actually having the gene itself.
So belief in the power of genetics turns out to undermine the power of genetics. This is more than a funny little paradox: the growth of the genetic-testing industry, and its ever deeper penetration into everyday life, depends on the premise that genes are ultimately meaningful. Advocates for more testing and classification treat genetic knowledge as a matter of existential truth, which it is pointless to avoid or deny.
Back in July, writing in the New York Times opinion section, psychology professor Kathryn Paige Harden spelled out this argument:
Our genes shape nearly every aspect of our lives — our weight, fertility, health, life span and, yes, our intelligence and success in school. Scientists have known this for years, based on results from twin and adoption studies, but it’s only recently that we have been able to measure DNA directly and use it to predict outcomes with any degree of certainty.
Genetic differences in human life are a scientific fact, like climate change. Many progressives resist acknowledging this when it comes to education, fearing that it will compromise their egalitarian beliefs. But just like acknowledging the reality of climate change is necessary to ensure a sustainably habitable planet, acknowledging the reality of genetic differences between people is a necessary step for us to ensure a more just society.
Harden was writing to argue that people on the left should get over their fears about the ugly history of eugenics and embrace genetic classification, so that genetic insights into people’s inborn ability levels could be used to shape a fairer educational system. This was naive unto evil as history or politics: the original eugenicists believed they were improving society, too, and the record abundantly shows that, given measures of genetic ability to work with, policymakers would not react by trying to “maximize a child’s potential” and even things out, but by deciding to write off the designated losers and reward the winners.
But this week’s study demonstrates that respectable neo-eugenics is wrong about the science, too. Genetic analysis does not produce a set of bottom-line facts; it identifies one set of limited explanations for what may happen in an incomprehensibly complex system. Claiming that there’s a moral or intellectual duty to track down, say, a good-at-school gene—that we have to “acknowledge the reality” of such knowledge—presumes that finding it actually would be knowledge, that the effects of such a gene would be more real than, say, the effects of just pretending you know about it.