At-home DNA kits are trying to make learning about your heritage and health one-click-simple. Before you jump into the gene pool, consider what experts say these tests can—and can't—reveal.

By Naomi Barr
September 23, 2019
Yasu + Junko

Think of at-home genetic tests as the new astrological star charts. They both confirm things you already know (Virgos are organized, for example, and Danes tend to be blond) and lure you in with the prospect of deeper insights. More than 26 million Americans, or about eight percent of us, have bought one—for ourselves, a family member, or a pet—and by 2021, that number is predicted to jump to about 30 percent. However, unlike horoscopes, the tests are based in medical science, and can have concrete takeaways. Yes, they can unveil long-lost third cousins or French lineage. But they also offer health details that, until fairly recently, you needed to make an appointment with a doctor or genetic counselor to discover.

Kits run the gamut in scope and cost. The least expensive ring up at under $100 and zoom in on a specific topic; for example, Orig3n's Hunger & Weight DNA test, which costs $49, reveals whether your tendency to hang onto extra pounds is genetic. For $199, you can get 23andMe's health-and-ancestry bundle, which includes a limited screening of gene variants related to celiac disease, late-onset Alzheimer's, type 2 diabetes, and breast and ovarian cancers, among other illnesses. It also tells you if you're a carrier for certain conditions, such as sickle-cell anemia, and generates a series of so-called wellness reports (such as your likelihood of being lactose intolerant or a caffeine junkie) and trait results (like whether you're predisposed to get bunions or fear heights).

Others, from companies such as Invitae and Color, are available in doctors' offices and online, and mostly look for cancers and heart conditions that can be treated before symptoms pop up; they're pricier (typically between $249 and $350) but more comprehensive, since they analyze more genes and variants, and connect you with a genetic counselor to interpret your results. Think of 23andMe as highlighting the key paragraphs in a book, while Invitae and Color summarize whole chapters and hold office hours. There are plenty of reasons to take one of these tests, from pure fun to disease prevention. Before you it or swab, weigh these pros and cons.

Related: How We Perceive Certain Smells Could Be Tied to Genetics, Says New Study

To Fill Out Your Family Tree

Looking for pros? You might learn that you're three percent Portuguese, or that you have seven new cousins within driving distance. And if your medical history is a mystery—maybe you're adopted, or your mom and dad aren't close with their parents or siblings—a test could give you a snapshot.

As for the cons, it's like opening Pandora's box; there's no predicting what you'll let out (you might have seven new half-siblings, not cousins, in town). "There are five things we tell people prior to a genetic test ," says Debra Mathews, PhD, a geneticist and assistant director for science programs at the Johns Hopkins Berman Institute of Bioethics, in Baltimore. "We could find nothing; we could find what we're looking for; we could find something we're not looking for; we could find variants we don't really under and; or we could find out your family structure isn't what you thought it was," like that your dad may not be your biological father, or that you're adopted. And this, she adds, happens more often than you might think.

Two medical caveats: Most genetic conditions are linked to hundreds if not thousands of variants, and consumer tests check only a small percentage of them. Plus, "much of the genomic data we have today is based on a narrow slice of the population, namely people of European descent, so the test may not be very helpful for people of African, Asian, Native American, or Latino backgrounds," says Mathews. "Until these databases become more diverse"—something companies are working on—"that leaves a large number of people out of the picture."

Related: How to Create a Family Tree

You're Health Obsessed—Okay, You're Totally a Hypochondriac

On the pro side, even if you already stay on top of taking care of yourself, some tests can cast a wider net. Per recent research led by Invitae, approximately one in six healthy DNA testers—about 16 percent—learn they may have a genetic risk for developing certain types of medical conditions. Your report could empower you to take preventive steps, or to simply make better lifestyle choices. "If a result gets you to think, 'Wow, I'm going to start watching what I eat and exercising more,' that's great," says Michael Stitzel, PhD, an assistant professor at the Jackson Laboratory for Genomic Medicine, in Farmington, Connecticut.

As for the cons, it's important to remember that risk is a relative term. "For some inherited disorders, like cystic fibrosis and Huntington's disease, having the associated variant puts your risk at 100 percent, meaning you're destined to get it," says Joel Eissenberg, PhD, a professor of biochemistry and molecular biology at Saint Louis University School of Medicine. "But in most cases, having a known variant only increases it to some point above average." (Sometimes that number is high enough to warrant action: Testing positive for a BRCA1 or BRCA2 variant can raise a woman's risk of developing breast cancer by up to 80 percent, and ovarian cancer by up to 54 percent—so knowing you carry one could potentially save your life.) Also, remember that DNA is just one variable: Risk is also influenced by age, environment, diet, physical activity, and medical and family history, among other factors.

 You Love a Person Quiz

If you're interested in finding out more about yourself, count these as pros: You'll get genetic "answers" to fascinating (to you) questions—Are you a thrill seeker or a worrier? Were you blessed with more brains or brawn? Which foods make your skin glow?—and can fine-tune routines accordingly.

In terms of cons, you'll need to remember that these tests aren't always great at individual predictions. Unlike those that screen for major medical conditions, which are based on research linking specific variants to significantly higher risk of a disease, wellness insights often pull results from genome-wide association studies. Translation: They look for common genomic signals in people who share a certain trait, but those commonalities may have very little impact on the subject of your test . "It's an association, not a causation," stresses Mathews. If you really want to know whether you're a deep sleeper or not, we have a better idea: Ask your bedmate.

Related: What You Need to Know About Pet DNA Kits

Your Chiweenie Has a Curly Tail

Here are a few pros for pet lovers: Knowing your pup's percentage of dachshund and Chihuahua, via a test from Wisdom Panel, Embark, or others, can help you tailor training and medical decisions, since certain personality traits, diseases, and conditions are common among certain breeds. Additionally, you may learn that Titus got his corkscrew tail from a pug ancestor. No dog? No worries. DDC Veterinary has avian, feline, and equine kits, too.

But there are cons, too. Like many tests for humans, these aren't 100 percent reliable. And not all companies check for all breeds—Wisdom Panel checks for more than 350; Embark lists over 250—so make sure the one you pick covers your dream dog. You could also, of course, learn that your beagle isn't a beagle at all—and if that's what your kids begged for, you might just decide to keep the results to yourself.

Martha Stewart Living, October 2019
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