There’s a lot more too it than just sending off some of your spit.
You can get varying results
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If you send your DNA to two different companies to find out your ancestry, you may end up with two different results. That’s because there’s no certification required for DNA-testing companies, and their methods aren’t independently validated, says Tufts University professor Sheldon Krimsky, PhD, board chair of the Council for Responsible Genetics. “They may get the basic idea correct—that you are a little less than half northern European, for example,” he says. “But when they say you’re 30 percent from here and 60 percent from there, it’s a statistical guess based on their own proprietary database and the statistical method they use.” Check out some of the most shocking DNA discoveries.
Your results will be less precise if you’re not European
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The more people from your ancestral region in a company’s database, the more accurate your results will be, says Hank Greely, director of the Center for Law and the Biosciences at Stanford Law School. Many Americans have northern and western European ancestry, and some evidence indicates they’re more likely to use DNA testing. “Even results from southern and eastern Europe aren’t as accurate,” Greely says.
It can’t tell you your tribe
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If you’re Native American or African American, no DNA test can tell you what tribe your ancestors belonged to. Testing companies that claim they can are misleading you, says Greely. These are the secrets ancestry trackers won’t tell you.
Go to a lab for conclusive results
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You can find out your risk of diseases such as cancer and Alzheimer’s from an at-home DNA test kit, but a laboratory certified to do medical testing will give you much more conclusive results. One small study found that 40 percent of at-home test kits were wrong about predicting genetic abnormalities. That said, many doctors support at-home testing so people can take preventive steps sooner.
The results of your genetic testing could affect your ability to get insurance
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While federal law prohibits health insurers from denying coverage based on genetic test results, the law does not apply to life, disability, and long-term-care insurance. In most states, an insurance company can legally ask for the results of your DNA test. “If you’re planning to get long-term-care or life insurance, buy it before you get tested,” Greely suggests.
They help solve crimes
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Law-enforcement agencies are increasingly using family tree DNA databases to solve crimes, as was done in the arrest of a former police officer accused of being the Golden State Killer. California detectives took the DNA results from various crime scenes, looked for partial matches on a public genealogy database, and eventually found their man.
You might be a suspect
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Of course, that also means a relative’s DNA could make you a suspect—even if you’re innocent. Exhibit A: New Orleans filmmaker Michael Usry was identified as a murder suspect based on a genetic sample his father had submitted years earlier as part of a church genealogy project. Usry was eventually cleared after further testing showed his DNA didn’t match the evidence from the crime scene. Privacy advocates oppose the government’s ability to use familial DNA, and Maryland and Washington, DC, prohibit its use in criminal cases. These medical mysteries were solved by DNA testing.
Your genetic information might be sold
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Your genetic information may be sold to the highest bidder—whether that’s a university or pharmaceutical company that wants to use it for research or a company mining it for profit, says Peter J. Pitts, president of the Center for Medicine in the Public Interest. Ask the testing company or read the small print before signing off.
There are privacy issues
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There’s another privacy issue: In 2017, the emails and passwords of more than 92 million users of the genealogy website myheritage.com were hacked, while Ancestry’s RootsWeb server exposed the emails, usernames, and passwords of 300,000 users.
Don’t fall for the advertisements
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The market is also exploding with companies claiming they can pinpoint the right product—for your skin or your waistline, for instance—based on a DNA test. But consider them entertainment rather than real science, Greely says. A study found that diets based on genetic tests didn’t help people lose weight.
They answer lots of questions
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Still, DNA tests can answer questions you’ve had about yourself—and ones you didn’t know to ask. For example, for an additional cost, 23andMe will include your results on more than 25 individual traits, including if you are likely to be a morning person, whether your hatred of cilantro is genetic, and if your earwax is more likely to be dry or wet.
They can’t predict athletic success
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Dozens of companies market DNA tests to coaches and parents that claim to predict a child’s athletic prospects. But there’s little science behind them, according to more than a dozen experts in genomics and sports performance.
Your DNA testing may reveal family secrets
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In just one among many such stories, a 23andMe user who tested himself and his parents for a class he was teaching on genetics unearthed a half brother. The revelation “uncorked” emotions with his family, he wrote on vox.com, and his parents eventually divorced. This is what doctors really think about genetic testing.
