“If you share, say, 25 percent of your DNA, then there’s a wider range of possible relationships,” Kennett says. The further away a relative is on the family tree, however, the less certain the results.
who helps people construct family trees using DTC testing and traditional methods, such as digging into historical records.įor instance, “relative matching” tests will always work with a parent or full sibling, she says.
“For close relationships, those predictions can be made very accurately,” says Debbie Kennett, a genetic genealogist in the U.K. The closer the relative, the more large DNA segments you’ll share.
How it works: To determine whether you might be related to another person in its customer database, a DTC testing company considers how many identical segments of DNA you have in common and the length of those segments. Here are four common claims from the manufacturers of these products, whether they deliver, and what to know about their potential pitfalls. A DTC test is more like throwing a net into the ocean and seeing what comes back.
Think of it this way: When your doctor orders genetic testing, it’s akin to fishing for a particular fish, in a part of the ocean where it’s known to live. If you send away your saliva for DTC genetic testing, however, the lab will look at a whole range of variants that have been linked-sometimes quite loosely-to a number of traits, some not related to your health at all. He says they will typically order tests focused only on that particular question, such as your inherited risk of cancer. When a doctor recommends genetic testing as part of your care, they’re usually aiming to answer a specific question about your health, says Kyle Brothers, MD, an associate professor in the department of pediatrics at the University of Louisville in Kentucky. Some variants are benign, some are linked to certain traits or illnesses, and many others are largely a mystery, their significance unknown. We all have small differences in our DNA code, known as variants, which genetic testing can reveal. (Find out why your genetic data isn’t safe.) And once data about your genes is shared, it can be sold or even potentially used to discriminate against you. “If you go in there thinking that this test is going to tell you who you are, you’re going to be wrong,” says Wendy Roth, PhD, an associate professor of sociology at the University of Pennsylvania in Philadelphia.Ī genetic test can also leave you with information you’d prefer not to have about your family or about your risk for an incurable disease. Manufacturers offer a variety of possibilities, including matching you with unknown relatives, telling you which country your ancestors came from, revealing your risk of certain illnesses, and even determining which diet is best for you.īut while these tests may offer potentially valuable genealogical or medical insights, experts say results may be easy to misinterpret or could be based on a misapplication of the science. And brands such as 23andMe and Ancestry are household names. The kits are wildly popular: About 1 in 5 Americans has taken a DTC genetic test, according to an October 2020 Consumer Reports nationally representative survey of 2,000 U.S. Users spit into a tube or swab the inside of their mouth to obtain DNA (molecules that form the building blocks of genes), mail the sample off, and receive an analysis a few weeks later. An endeavor that originally involved billions of government dollars and collaboration among thousands of scientists around the globe has yielded not just medical progress but also a slew of consumer products in the form of at-home genetic tests.įor a relatively modest fee, anyone can purchase a direct-to-consumer (DTC) genetic test kit. This knowledge, however, is also being used toward somewhat less profound ends. Almost two decades later, genomics has led to critical progress in medical science, particularly in identifying individuals’ genetic predispositions to diseases such as breast cancer.