Sigmund Freud, in “Family Romances,” writes that all of us, once we realize as children the uncertainty of paternity, begin fantasizing about alternative fathers. (In my fantasy, my father owned a gumball-machine empire, and I was an heiress with bad teeth.) But Grethel pointed out that the desire for a perfect do-over with a new parent can lead to profound disappointment. In 2012, the Canadian actress and director Sarah Polley learned that her biological father was the film producer Harry Gulkin, a discovery she documented in the film “Stories We Tell.” “There was this honeymoon period,” Polley told me, of the year after she reconnected with Gulkin. “It was exciting—like, Wow, what a twist—but then it became quite tumultuous.”

“God works in mysterious ways.”

Cartoon by Sam Gross

Michael Slepian, a psychologist at Columbia University, researches the toll of keeping secrets. For his book, “The Secret Life of Secrets: How Our Inner Worlds Shape Well-Being, Relationships, and Who We Are,” Slepian asked research participants—half of whom were told to imagine themselves as having a “small” secret, the other half a big one—to estimate the height of a grassy hill. The latter group thought that the incline was sharper than the former did. Slepian deduced that people who say they feel “weighed down” by a secret do, in fact, feel burdened in other parts of their lives as well. The night after Slepian first presented his findings at Columbia, he got a frantic call from his father. He and his mother had realized that they, like his subjects, had been suffering under the weight of a secret. Slepian had been conceived through a sperm donor, his father confessed over the phone. “Many people assume it was the other way around,” Slepian told me, “that I research secrets because my family had been keeping one. But no—my research helped them unburden themselves.”

Slepian also studies the moral calculus of divulging a secret, like, for example, when and whether to reveal to a partner that you were unfaithful. He thinks that, in the context of N.P.E.s, technology has altered the question of disclosure: “I know folks who wished they’d learned this from their parents rather than a website.”

The treatment of N.P.E.s is a growth market within the therapy sector, giving rise to N.P.E.-trauma-recovery coaches and identity-reinvention facilitators. Some interventions can seem more improvised than others. Lily Wood mentioned that she had been using eye movement desensitization and reprocessing (E.M.D.R.) to help her reckon with her discovery. This method typically involves having patients focus on a specific traumatic event; I asked Wood whether hers was the day she got the results. No, she said. Her therapist had her doing “point of conception” E.M.D.R.: “She’s, like, ‘I don’t do this very often, but we’re going to go back to the moment you were in utero. . . . Babies feel everything, even as a fetus.’ ” Wood was a little dubious herself. “I’m only on the third trimester, so I don’t know if it’s working yet,” she said.

Alexis Hourselt grew up in Tucson, Arizona, as the daughter of a Mexican American father and a white mother. Hourselt never felt a connection with her Mexican heritage, though. “I wanted to, being in the Southwest,” she told me. Rather, she was drawn to Issa Rae’s “Insecure” and the later, more politically inflected music of Beyoncé. “I loved ‘Formation,’ but I always thought, This isn’t for me.”

At some point, Hourselt added an Ancestry test to her Amazon wish list, which her family members all follow. She hoped that the test would uncover more about her Indigenous roots, and help her feel more connected to her father’s side. “Nobody ever bought it for me—which now makes sense,” she reflected. She purchased one for herself when it went on sale for Prime Day.

One afternoon, while waiting for the results, Hourselt was folding laundry and suddenly had an intrusive thought. “I was, like, Wouldn’t that be crazy if your dad wasn’t your dad? And then I was quickly, like, Stop it. You’re so ridiculous.” But, when the e-mail came and she clicked on her DNA map, the thought returned. Her DNA did not cluster with that of anyone in Mexico. Lit up instead was the western coast of Africa—countries like Nigeria, Mali, and Cameroon—and the African American population of North Carolina. “I called my mom, and she acted surprised but in a way that very much let me know that she was not surprised,” Hourselt told me.

Hourselt, who, since 2022, has hosted the podcast “DNA Surprises,” invited me to Tucson for dinner with her family: her husband and kids; her sister Amanda; and her parents, meaning her mother, Carole, and Jaime, the father who raised her. A week before I was scheduled to come, Hourselt told me that Jaime had a conflict and wouldn’t be joining us. I didn’t probe. When I arrived, I was greeted by Hourselt, in a colorful Ankara-print baby-doll dress, and the smell of sautéed onions; her husband, Josh, was preparing fajitas. Her mother sat on the living-room couch in a gray sweatshirt, holding a pink Stanley cup. She looked uncomfortable.

We sat down for dinner, and together they took me back to July 22, 2021, Hourselt’s rebirth day. After the phone call, Carole and Jaime went over to their daughter’s house. Carole couldn’t stop crying, so Jaime did all the talking. “He said, ‘I met you when you were two months old,’ ” Hourselt recalled. She was taken aback. “I thought, Maybe Mom had an affair or something. It didn’t register to me as a possibility that he would be in on it.” The couple had been stationed together in the military, in Spain. Carole, then a new mother, told Jaime that her baby’s biological father was her Puerto Rican ex-boyfriend; the end of their relationship, she said, had been rocky. But that didn’t make sense to Hourselt. Her Ancestry matches had uncovered that her biological father was very likely an African American man. Carole swore that she didn’t remember the encounter, but the revelation then created problems in her marriage. “Jaime said, ‘I didn’t realize I’d married a floozy,’ ” she recalled. “And that’s the nice term for what he said.”