DNA Tests Are Uncovering the True Prevalence of Incest

When Steve Edsel was a boy, his adoptive parents kept a scrapbook of newspaper clippings in their bedroom closet. He would ask for it sometimes, poring over the headlines about his birth. Headlines like this: “Mother Deserts Son, Flees From Hospital,” Winston-Salem Journal, December 30, 1973.

The mother in question was 14 years old, “5 feet 6 with reddish brown hair,” and she had come to the hospital early one morning with her own parents. They gave names that all turned out to be fake. And by 8 o’clock that evening, just hours after she gave birth, they were gone. In a black-and-white drawing of the mother, based on nurses’ recollections, she has round glasses and sideswept bangs. Her mouth is grimly set.

The abandoned boy was placed in foster care with a local couple, the Edsels, who later adopted him. Steve knew all of this growing up. His parents never tried to hide his origins, and they always gave him the scrapbook when he asked. It wasn’t until he turned 14, though, that he really began to wonder about his birth mom. “I’m 14,” he thought at the time. “This is how old she was when she had me.”

Steve began looking for her in earnest in his 20s, but the paper trail quickly ran cold. When he turned 40, he told his wife, Michelle, that he wanted to give the search one last go. This was in 2013. AncestryDNA had started selling mail-in test kits the previous year, so he bought one. His matches at first seemed unpromising—some distant relatives—but when he began posting in a Facebook group for people seeking out biological family, he got connected to a genetic genealogist named CeCe Moore. Moore specializes in finding people via distant DNA matches, a technique made famous in 2018 when it led to the capture of the Golden State Killer. But back then, genetic genealogy was still new, and Moore was one of its pioneers. She volunteered to help Steve.

Within just a couple of weeks, she had narrowed down the search to two women, cousins of the same age. On Facebook, Steve could see that one cousin had four kids, and she regularly posted photos of them, beautiful and smiling. They looked well-off, their lives picture-perfect— “like a storybook,” Steve says. The other woman was unmarried; she didn’t have kids. She was not friends with her immediate family on Facebook, and she had moved halfway across the country from them. One evening—a Saturday, Steve clearly remembers—Moore asked to speak with him by phone.

She confirmed what he had already suspected: His birth mom was the second woman. But Moore had another piece of news too. She had unexpectedly figured out something about his biological father as well. It looks like your parents are related. Steve didn’t know what to say. Do you understand what I mean? He said he thought so. Either your mom’s father or your mom’s brother is your father. A sea of emotions rose to a boil inside him: anger, hurt, worthlessness, disgust, shame, and devastation all at once. In his years of wondering about his birth, he had never, ever considered the possibility of incest. Why would he? What were the chances?

In 1975, around the time of Steve’s birth, a psychiatric textbook put the frequency of incest at one in a million.

But this number is almost certainly a dramatic underestimate. The stigma around openly discussing incest, which often involves child sexual abuse, has long made the subject difficult to study. In the 1980s, feminist scholars argued, based on the testimonies of victims, that incest was far more common than recognized, and in recent years, DNA has offered a new kind of biological proof. Widespread genetic testing is uncovering case after secret case of children born to close biological relatives—providing an unprecedented accounting of incest in modern society.

The geneticist Jim Wilson, at the University of Edinburgh, was shocked by the frequency he found in the U.K. Biobank, an anonymized research database: One in 7,000 people, according to his unpublished analysis, was born to parents who were first-degree relatives—a brother and a sister or a parent and a child. “That’s way, way more than I think many people would ever imagine,” he told me. And this number is just a floor: It reflects only the cases that resulted in pregnancy, that did not end in miscarriage or abortion, and that led to the birth of a child who grew into an adult who volunteered for a research study.

Most of the people affected may never know about their parentage, but these days, many are stumbling into the truth after AncestryDNA and 23andMe tests. Steve's case was one of the first Moore worked on involving closely related parents. She now knows of well over 1,000 additional cases of people born from incest, the significant majority between first-degree relatives with rest between second-degree relatives(half-siblings, uncle-niece, aunt-nephew, grandparent-grandchild). The cases show up in every part of society, every strata of income, she told me.

[Read: When a DNA Test Shatters Your Identity]

Neither AncestryDNA nor 23andMe informs customers about incest directly, so the thousand-plus cases Moore knows of all come from the tiny proportion of testers who investigated further. This meant, for example, uploading their DNA profiles to a third-party genealogy site to analyze what are known as “runs of homozygosity,” or ROH: long stretches where the DNA inherited from one’s mother and father are identical. For a while, one popular genealogy site instructed anyone who found high ROH to contact Moore. She would call them, one by one, to explain the jargon’s explosive meaning. Unwittingly, she became the keeper of what might be the world’s largest database of people born out of incest.

In the overwhelming majority of cases, Moore told me, the parents are a father and a daughter or an older brother and a younger sister, meaning a child’s existence was likely evidence of sexual abuse. She had no obvious place to send people reeling from such revelations, and she was not herself a trained therapist. After seeing many of these cases, though, she wanted people to know they were not alone. Moore ended up creating a private and invite-only support group on Facebook in 2016, and she tapped Steve and later his wife, Michelle, to become admins, too. The three of them had become close in the months and years after the search for his birth mom, as they navigated the emotional fallout together.

One day this past January, Michelle, who also works as Moore’s part-time assistant, told me she had spoken with four new people that week, all of them with ROH high enough to have parents who were first-degree relatives. She used to dread these calls. “I would stumble over my words,” she told me. But not anymore. She tells the shaken person on the line that they can join a support group full of people who are living the same reality. She tells them they can talk to her husband, Steve.

When Steve first discovered the truth about his biological parents, a decade ago, he had no support group to turn to, and he did not know what to do with the strange mix of emotions. He was genuinely happy to have found his birth mom. He had never looked like his adoptive parents, but in photos of her and her family, he could see his eyes, his chin, and even the smirky half-grin that his face naturally settles into.

But he radiated with newfound anger, too, on her behalf. He could not know the exact circumstances of his conception, and his DNA test alone could not determine whether her older brother or her father was responsible. But Steve could not imagine a consensual scenario, given her age. The bespectacled 14-year-old girl who disappeared from the hospital had remained frozen in time in his mind, even as he himself grew older, got married, became a stepdad. He felt protective of that young girl.  

As badly as he wanted to know his birth mom, he worried she would not want to know him. Would his sudden reappearance dredge up traumatic memories—memories she had perhaps been trying to outrun her whole adult life, given how far she had moved and how little she seemed connected to her family? A religious man, Steve prayed over it and settled on handwriting a letter. He included a couple of paragraphs about his life, some photos, and a message that he loved her. He left out what he knew about his paternity. And he took care to send the letter by certified mail, so that he could confirm its receipt and so that it would not accidentally fall into anyone else’s hands.

She never responded. But Steve knew that she had received it: The post office sent him the green slip that she had signed upon delivery, and he scrutinized her signature—her actual name, written by her actual hand. At 40 years old, he touched for the first time something his mother had just touched, held something she had just held. He put the slip inside the pages of his Bible.

Steve had never faulted his mother for leaving him at the hospital, and finding out about his paternity made him even more understanding. But the revelation also made him struggle with who he was. Did it mean that something was wrong with him, written into his DNA from the moment of his conception? On a podcast later, he admitted to feeling like trash, “like something that somebody had just thrown away.” Those first six months after his discovery were the hardest six months of his life.

Across human cultures, incest between close family members is one of the most universal and most deeply held taboos. A common explanation is biological: Children born from related parents are more likely to develop health complications, because their parents are more likely to be carriers of the same recessive mutations. From the 1960s to the ’80s, a handful of studies following a few dozen children born of incest documented high rates of infant mortality and congenital conditions.

But in the past, healthy children born from incestuous unions would have never come to the attention of doctors. As widespread DNA testing has uncovered orders of magnitude more people whose parents are brother and sister or parent and child, it’s also shown that plenty of those people are perfectly healthy. “There is a large element of chance in whether incest has a poor outcome,” according to Wilson, the geneticist. It depends on whether those runs of homozygosity contain recessive disease-causing mutations. All of us have some of these runs in our DNA—usually less than 1 percent of the genome in Western populations, higher in cultures where cousin marriage is common. But that number is about 25 percent, Wilson said, in people born from first-degree relatives. While the odds of a genetic disease are much higher, the outcome is far from predetermined.

Still, these numbers make people wonder. Steve was born with a heart murmur, which required open-heart surgery at ages 13 and 18, though he does not know for sure the cause; heart defects are among the more common birth defects in the general population. He and Michelle were also never able to have children together. Others in the Facebook group have shared their struggles with autoimmune diseases, fibromyalgia, eye problems, and so on—though these are often hard to definitively link to incest. Health problems arising from incest might manifest in any number of ways, depending on exactly which mutations are inherited. “When I go to the doctor and they ask me my family history, I wonder: How much do I need to go into it?” says Mandy, another member of the group. (I am identifying some people by first name only, so they can speak freely about their family and medical histories.) How much experience would a typical doctor have with incest, anyway?

After Mandy first learned that her father was her mother’s uncle, she went looking for stories about other people like her. All she could find were “gross fantasies” online and medical-journal articles about health problems. She felt very lonely. “I don’t have anybody I can talk to about this,” she remembers thinking. “Nobody knows what to say.” When she found the Facebook group, she could see that she was far from the only one like her. She watched the others cycle, too, through the stages of denial, anger, bargaining, depression, and acceptance.

She does not know exactly what happened between her biological parents, but her mother was 17, and her mother’s uncle was in his 30s. The discovery, for all the hurt that it surfaced, has helped Mandy reconcile some of her childhood experiences. Unlike Steve, she was raised by her biological mother, and she believed her mother’s husband to be her biological father. He mostly ignored her, but her mother was cruel. She treated Mandy differently than she did her younger brothers. “At least now I have more of an answer as to why,” Mandy told me. “I wasn’t a bad kid and unlovable.”

Kathy was also raised by her mother, though she had an early inkling that her dad was not her biological dad. Their blood types were incompatible, and she heard rumors about her mother and grandfather. Although her mother’s family was violent and chaotic, she was close to her dad’s family, especially her granny on that side. “They’ve been my rock,” she told me. By the time Kathy took a DNA test confirming that her dad was not her biological dad, she had spent a lifetime distancing herself from her biological family and embracing one with whom she shared no DNA.

Hers was, in some ways, the opposite journey of adoptees such as Steve, who wanted so badly to know his biological family. But the two of them have become close. Kathy remembers how angry he used to be on his mother’s behalf. She told him that she used to be angry too, but she had to leave it behind. “It’s not going to bring me any peace. It’s not going to bring my mother any peace,” she recalled saying. And it wouldn’t undo what had been done to his mother by her father or her brother so many years ago.

In the end, Steve was able to identify his biological father, though not through any particular feat of genetic sleuthing. One day, two and a half years after his DNA test, he logged in to AncestryDNA and saw a parent match. It was his mother’s older brother. From the site, he could see that his father-uncle had logged in once, presumably seen that Steve was his son, and—even after Steve sent him a message—never logged back on again.

By then, his initial anger had started to dissipate. He still felt deeply for his birth mom. Michelle says that her husband has always been a sensitive guy—she makes fun of him for crying at movies—but he’s become even more empathetic. The feelings of worthlessness he initially struggled with has given way to a sense of purpose; he and Michelle now spend hours on the phone talking with others in the support group.

Steve has still never spoken to his birth mother. He tried writing to her a second time, sending a journal about his life—but she returned it unopened. He messages her occasionally on Facebook, sending photos of grandkids and puppies he’s raised. Every year, he wishes her a happy birthday. She has not replied, but she has also not blocked him.

When the journal came back unopened, Steve decided to try messaging his mother’s cousin—the other woman he’d initially thought could be his birth mom. He yearned for some kind of connection with someone in his biological family. He wrote to the cousin about his mom—but not his dad—and she  actually replied. She told him that she and his mom had been close as children, Steve recounted, but she did not know about a pregnancy. To her, it had seemed like her cousin one day “fell off the face of the Earth,” he says. She agreed to read his journal, and the two of them soon began speaking on the phone about their families.

Months later, Steve felt like he could finally share the truth about his biological father, and the cousin again accepted him for who he was. They met for the first time in 2017 when she was visiting a nearby town, and she later invited Steve and Michelle to Thanksgiving. Last year, she extended another invitation to a large family gathering. Steve’s immediate biological family was not there, but hers was, and they all knew about him and his mom and his dad. They greeted him with hugs, and they took photos together as a family. “It felt like a relief,” he told me, like a burden had been lifted from him. In this family, he was not a secret.