The Dark Side of DNA: How Genetic Tests Expose Family Secrets (And Why They’re Not Perfect)

DNA tests are fun...until you find out about your family's darkest secrets. We took a closer look at some shocking stories of DNA testing gone wrong.

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If you’re curious about your heritage, you can always take one of those trendy DNA tests. Sites like 23andMe and AncestryDNA offer users the opportunity to take a closer look at their genetics, and by all accounts, they’re largely accurate. There’s no easier way to find out if you truly have Scandinavian heritage, or if you’re Irish enough to celebrate St. Patrick’s Day guilt free.  In 2017 alone, about 12 million Americans purchased genetic genealogy tests. That means around 1 out of every 25 American adults have access to detailed genetic information—and, by all accounts, that number is going up.  However, there’s a dark side to online genetic tests: They occasionally unearth uncomfortable information. In fact, the major DNA testing sites explicitly warn their users about that possibility. “You may discover unexpected facts about yourself or your family when using our services,”’s privacy page warns. “Once discoveries are made, we can’t undo them.” Granted, these situations are rare, but when they occur, they have life-altering consequences. We looked into a few cases where people received results they weren’t expecting (and what happened next).

1. A woman learns that she has more in common with her husband than she’d anticipated.

Liane Kupferberg Carter met her husband Marc during a vacation in Nassau. It was a storybook romance—or, as she described it in a piece for The Cut, “rom-com cute.” “I was 25; he was two years older,” she wrote. “Initially, he was chasing my roommate. We struck up an intense conversation on the plane home, and by the time we landed at JFK, I had the unbidden thought, ‘I could marry a guy like this.’” Spoiler alert: She married him. After arriving home, Liane discovered that Marc lived one block away from her Manhattan apartment. Flash forward a few years, and they were planning their lives together. They tied the knot, and everyone lived happily ever after. Well, sort of. 38 years later, Liane signed up for 23andMe, and one day, she received an email: “You have new DNA relatives.” The relative in question was her husband, Marc. He was her third cousin. Before you get all creeped out, it’s important to know that third cousins don’t have a significantly higher risk of birth abnormalities than totally unrelated people. In fact, one Icelandic study showed that third- or fourth-cousin couples tend to be well suited biologically and typically have more kids than other couples. There’s even some research suggesting that first cousins’ risks are only a few percentage points higher than other couples (and cousin marriage was fairly common throughout history—Albert Einstein, Charles Darwin, and Edgar Allan Poe all married their cousins, and we certainly don’t look at them like they’re rogue Game of Thrones characters). 

One of Carter’s children has an epileptic disorder and autism, but there’s no clear link between the couple’s genetic similarity and the boy’s conditions. While Liane admits that her unexpected genealogical revelation gave her some pause, she never doubted that her husband was the right man for her. “I don’t need the imprimatur of 23andMe to tell me what I already know with bone-deep certainty: our connection is a decades’ long conversation that continues to nurture and sustain us both,” she wrote. In other words, she’s, uh, glad she married her cousin. 

2. A woman gets a DNA test for Christmas (and loses her sense of identity).

Linda Ketchum of Glendale, California received an AncestryDNA test from her husband as a Christmas present. Per a report in The New York Post, she wasn’t expecting much; she simply wanted to trace back her heritage. “My dad was German, and my mother was Scottish-English,” she told the paper. “I thought it’d be fun to learn a little about my genetic ethnicity, to trace how all the pieces came together.” Unfortunately, the results were fairly dramatic. Ketchum discovered that she had no biological link to her father whatsoever. Instead, she had numerous connections to Hispanic people in the site’s database.  “At first I didn’t believe it,” she said. “But then I kept re-checking it, and I realized, ‘Oh my God, does this mean I’m…I’m Hispanic!’” Her real biological father was a man of Hispanic descent. As both of her parents were deceased, she had nowhere to turn for answers. “All these years I thought I was German on my dad’s side, but all of a sudden it was dawning on me that my dad wasn’t my real dad and I had an entirely different ethnicity.” Ketchum told the paper that she was fairly traumatized. She lost her identity, and she began wondering whether she was related to random Hispanic people she saw on the street. She eventually tracked down her real biological father, Bill Chavez, who lived in New Mexico. He had also passed away, so she wasn’t able to connect with him. Ketchum’s story doesn’t have a happy ending, per se, but she’s at peace with the discovery. Still, she frequently thinks about the family she never met. “I still wonder sometimes, would my life have been different if I’d known this earlier?” she said. “My real father, my actual grandparents, they all spoke fluent Spanish. I can’t even speak a word of it!”

3. A CNBC anchor receives shocking information (and ends up writing a book).

Journalist Bill Griffeth took a DNA test in 2012, hoping to learn more about his European ancestors. He’d had an ongoing interest in genealogy—he’s on the board of Boston’s New England Historic Genealogical Society—and he had even written a book about his ancestors’ journey to the United States. Griffeth was extremely proud of his family, and when his cousin asked him to participate in genetic testing to get more information about their family origins, he happily agreed.

Hey, he’s part of this article, so you probably know where this is going. The test showed that Griffeth had no biological relation to his late father. When he received word via email, he was crushed. “My body responded before my brain could,” Griffeth wrote in his memoir The Stranger in My Genes. “I experienced a strange sensation of floating, and I could no longer feel the chair I was sitting in or the Blackberry I was holding. My breathing became labored and shallow and I heard a roaring in my ears like ocean waves crashing off in the distance.” Initially, Griffeth denied the results, insisting that the company that tested his DNA had made some mistake. He actually went on the air on CNBC within hours of receiving the news and acted as though nothing had happened. For months, he refused to accept reality. Eventually, the truth set in: His mother had had an affair, which she’d hidden from her family for decades. He eventually decided to confront her with the information.

“There was a time when I said, ‘I don’t want to pursue this any further, I don’t want to trouble Mom with it,’” Griffeth told the Extreme Genes podcast. “But as my brother said, ‘What if you want answers eventually and she’s gone, what are you going to do? And what about your children, they’re going to need answers down the road?’” “We really needed to know the truth, so I presented her with the DNA evidence, and she took it like a champ. She admitted that she had made a mistake when she was younger, and that was that.” These days, Griffeth is at peace with his family history. He doesn’t discuss the matter with his mother, but when he decided to write a book about his experience, she gave him her blessing.

“We don’t talk about it anymore,” he said. “…She’s of a different generation, a different time.” Since going public with his story, Griffeth has heard from dozens of people about their own DNA testing mishaps. He says his perspective has gradually changed; he knows if his mother hadn’t made her “mistake,” he wouldn’t be here, and he takes comfort in knowing his situation isn’t unique. “The only takeaway I can have from this is to be grateful about it,” he said. “…I encourage anybody, if you’re going through this, reach out. It’ll be a difficult first step, but you gotta be able to tell somebody.” “I just think that DNA testing is going to have a profound impact, not only on biotechnology and medicine—it’s already having an impact there—but I think it’s going to have a profound impact on our social culture.”  

4. A woman gets a doctor-ordered DNA test, with tragic results.

While many people get DNA tests to learn about their hereditary history, some choose to get tested for medical reasons. Certain hereditary conditions have genetic markers that can help doctors diagnose, prevent, and even cure diseases before they become life threatening. In fact, many direct-to-consumer DNA testing services like 23andMe offer specialized tests for these genetic markers—but they warn that people shouldn’t make medical decisions based on their screenings. Maureen Boesen has a family history of cancer, and she and her two sisters entered a university study to determine whether or not they had a BRCA gene mutation that would raise her risk of developing the disease. Boesen tested positive.

“It was just devastating because I knew what breast cancer and ovarian cancer can do to a family,” she told KSHB in Kansas City. “The first question out of my mouth was, ‘Is there any chance this could be wrong?’ And the researcher said ‘No.’” To limit her chances of developing cancer, Boesen underwent a preventive double mastectomy at 23. Years later, she also decided to undergo a complete hysterectomy, but prior to that procedure, doctors performed another test.

“I was at work, and the first thing [the doctor] said was, ‘We need to talk,’” she recalled. “And my heart just sank. And she said, ‘You’re negative!’ and I just started bawling. I was angry. I was regretful. I was happy. I was sad.” According to the U.S. Preventive Service Task Force’s recommendations for BRCA testing, doctors should screen some women with cancer in their family histories, but false positives occur occasionally. It’s unclear why Boesen’s physicians didn’t re-test her before carrying out her double mastectomy, but her story is a good indication of how genetic tests can be misleading—and why a second opinion is always helpful when making serious medical decisions.  “I wish what I had been told was, ‘If you don’t trust it, get another test,’” Boesen said. “But that’s not what I was told, and my life could have been so different.”

5. A woman finds out a secret about her family…but decides to do some investigating.

Kristen Brown received a shock when her aunt sent off for a commercial DNA test: According to the results, Brown’s grandfather wasn’t a full-blooded Syrian. That led to a small family scandal. “If we weren’t who we thought we were, well, then, who were we?” Brown wrote for Gizmodo. But to Brown, something didn’t seem right. She suspected that the test was inaccurate, so she mailed DNA samples to three major commercial DNA testers…and received extremely different results from each. She’s not the only one. In 2018, reporter Rafi Letzler took nine DNA tests from three companies and received six distinctly different results. Even when a single company performs a test multiple times, the results can change dramatically. How could that happen? For starters, those heritage estimates (think “you’re 9 percent Scandinavian” and other such results) are just that—estimates—and they’re not as accurate as you might assume.  To determine users’ heritage, sites compare the DNA of all of the people who’ve already taken the test. If a person’s genetic makeup is more similar to, say, the DNA of Scandinavian users, the service will conclude that the user has some Scandinavian heritage. However, the services can only work with whatever data is available. Heritage estimates will vary from one site to the next—if the site has a lot of Italian users, it’s more likely to provide accurate heritage estimates for people with Italian backgrounds, and conversely, if the site’s database doesn’t have many Middle Eastern samples to use as a comparison point, it will have trouble accurately determining the heritage of a person with a Middle Eastern background. “Your DNA is only part of what determines who you are, even if the analysis of it is correct,” Brown wrote. “…If the messaging of consumer DNA companies more accurately reflected the science, though, it might be a lot less compelling: Spit in a tube and find out where on the planet it’s statistically probable that you share ancestry with today.” That’s not to say that commercial genetic tests are worthless; they can provide some useful information about heritage, and they can accurately determine relationships between different users. But if you assume that the tests are perfect, the results are in: You’re 99 percent naive. 

HealthyWay Staff Writer
HealthyWay’s Staff Writers work to provide well-researched, thought-provoking content.