“I didn’t want to spend my time calculating whether or not I had the gene,” she says. She was okay with the secrecy. She was okay with undergoing IVF—even though she could have kids naturally if she got tested and found out she was negative for the Huntington’s mutation. But getting tested meant a 50-50 chance of finding out she was positive. She couldn’t risk that.

Not wanting to know is quite common among people at risk for Huntington’s. A genetic test that predicts almost perfectly whether someone will develop the disease has been available since the late 1980s, but only 8 percent of people at risk choose to test, according to the Huntington’s Disease Society of America. There is currently no cure for Huntington’s, and very little can be done for anyone with the disease. All someone at risk for Huntington’s might gain is certainty of how he or she will die. For this reason, a niche IVF market has sprung up for people like Leyton who want no foresight of their own future but want to keep their children from ever worrying about the disease.

After creating embryos through IVF, a patient can choose to screen them through a procedure called nondisclosure preimplantation genetic testing for monogenic disorders, or PGT-M. (It is also sometimes called preimplantation genetic diagnosis or PGD.) Most people who get PGT-M for Huntington’s are already aware of their status, and do not want to pass on the risk to their children.

Nondisclosure PGT-M is for people who do not want to know their status. These procedures are quite rare, but they exist in possibly one of the most unusual corners of modern medicine—where information is deliberately kept from the patient.

Leyton was one of the first people to undergo nondisclosure testing for Huntington’s in the late 1990s. She was living in New York at the time, but the only clinic she could find offering the procedure was the Genetics & IVF Institute in Fairfax, Virginia. She and her husband got extremely familiar with the drive down from New York. To monitor her hormone levels in between, she would regularly get her blood drawn in New York City and FedEx it to Fairfax. “You would have thought I was the dumbest person on Earth,” she says of having to mail her blood to Virginia. “All I wanted was to have a baby.” She ultimately had healthy twins, a boy and a girl.

Leyton chose what’s called direct nondisclosure testing, in which doctors would find out her Huntington’s status but keep it from her. Doctors at the Genetics & IVF Institute first proposed using this type of testing for Huntington’s in a 1996 paper. It was controversial, especially in Europe. Physicians there objected particularly to mock transfers, in which the fertility clinic still pretends to implant embryos, even if none of the resulting embryos are free of the Huntington’s mutation. To skeptics, this scenario captured the extreme lengths necessary to maintain nondisclosure.