Can Knowing Your Genetic Risk Change Your Physiology?

We now have unprecedented amounts of information on our own genetics, thanks to at-home DNA testing kits. But what does all of this information do to us? Can simply knowing more about your genetic risks change them?

Sabrina Stierwalt, PhD
4-minute read
Episode #316
image of woman running on treadmill

In quantum mechanics, there is a pervasive theory known as the “observer effect,” which states that the act of observing a phenomenon (usually by making some kind of measurement) necessarily changes that phenomenon. In other words, just by being there and having an interest in the outcome, we affect that outcome.

Does simply knowing more about our own physiology change it?

While the explanations behind the observer’s influence in quantum mechanics come down to the measuring instrument and not the observer’s conscious mind, we also see strong evidence for the placebo effect in medicine: a patient’s condition can improve if they just believe they are receiving an effective treatment. And those beneficial effects can happen even if the patient is not actually receiving that treatment or if the treatment doesn’t actually work.

So is there such a thing as too much information? We now live in an age where mountains of detailed statistics on our own genetics are readily available thanks to DNA testing companies like 23andme and Ancestry DNA. At the same time, we continue to make significant progress toward mapping the human genome and understanding which genes are linked to our specific physical traits.

If our minds truly do have power over our surroundings and our bodies, what does having all of this genetic information do to us? Does simply knowing more about our own physiology change it? A recent study on exercise and obesity suggests that the answer is yes.

What happens when you learn of a genetic risk?

In this study, led by researchers at Stanford in the group of Dr. Alia Crum, participants performed differently on tests related to fitness and weight gain after they were told of their genetic risks toward either. Interestingly, that difference in performance was seen whether the genetic risk information they were given was true or not.

For the study, 116 people performed an initial fitness test on a treadmill and 107 people participated in the diet side of the investigation by eating a meal. Researchers looked for participants’ ability to perform well on the treadmill test and, in the case of the eaters, measured their levels of certain molecules in the blood that act as markers for hunger or fullness. They had also previously tested the study’s participants’ DNA for genetic predispositions toward both fitness capacity and obesity. The initial results showed small trends linking performance and the genetic tracers: for example, those with the beneficial exercise gene did slightly better on the treadmill.

Here is where things get interesting. The study participants came back a week later to take the test again but this time they were given information on their genetic test results that was sometimes true but sometimes false. They were further specifically told what those genetic results would imply as far as their performance on the treadmill or eating tests. For example, the eaters who were told they were at higher genetic risk for obesity were given the information that the presence of the variant in the so-called obesity gene (known as FTO) could mean their bodies produce less of the hormone that signals a feeling of being full to the brain.

The results of the second round of testing revealed that just telling people they were predisposed toward certain physical traits had a noticeable effect on their performance related to those traits, regardless of whether or not the genetic information they were given was true.

Those who were told they were at low genetic risk for obesity produced 2.5 times more of the fullness hormone and claimed to feel fuller despite eating the same meal as they had one week prior. Those who were told they were genetically predisposed toward lower endurance did worse on their treadmill test than they had prior to receiving that information: they showed lower lung capacity and quit sooner.

The results of the second round of testing revealed that just telling people they were predisposed toward certain physical traits had a noticeable effect on their performance related to those traits.

Thus, having information about our genetic risk can lead to improvements in our physiology (as was true for the eaters of the study), but it can also put us at a disadvantage (as with the poor exercise performers). So we certainly need to be wary of incorrect genetic information. But as the Stanford study shows, even if the genetic information we receive is correct, how we receive it is also important. In the case of the study, participants were quickly told the goals and results of the study as well as given their proper results. But the rest of us do not have such a clear view on how our brain chemistry translates our newfound genetic knowledge into our more readily observable physical traits.

Phenomena like the more well-known observer effect or the placebo effect can be difficult to understand because they confuse our idea of cause and effect. Treatments proven ineffective should not lead to beneficial results—but they can if patients believe they are being treated effectively. We do not yet know where genetic knowledge falls on the spectrum of clear cause and effect. Learning more about how being told of our genetic risks affects our brain chemistry and our physiology will become increasingly important as humans gain more and more easy access to our genetic information.

Until next time, this is Sabrina Stierwalt with Everyday Einstein’s Quick and Dirty Tips for helping you make sense of science. You can become a fan of Everyday Einstein on Facebook or follow me on Twitter, where I’m @QDTeinstein. If you have a question that you’d like to see on a future episode, send me an email at everydayeinstein@quickanddirtytips.com.

About the Author

Sabrina Stierwalt, PhD

Dr Sabrina Stierwalt earned a Ph.D. in Astronomy & Astrophysics from Cornell University and is now a Professor of Physics at Occidental College.

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