“You build your whole life on your genetic identity, and that’s the foundation,” Ms. Wiley said. “But when those bottom bricks have been removed or altered, it can be devastating.”

Through his attorney and the staff at his office, Dr. McMorries declined to comment.

With the advent of widespread consumer DNA testing, instances in which fertility specialists decades ago secretly used their own sperm for artificial insemination have begun to surface with some regularity. Three states have now passed laws criminalizing this conduct, including Texas, which now defines it as a form of sexual assault.

Dr. Jody Madeira, a law professor at Indiana University, is following more than 20 cases in the United States and abroad. They have occurred in a dozen states, including Connecticut, Vermont, Idaho, Utah and Nevada, she said, as well as in England, South Africa, Germany and the Netherlands.

According to the Dutch Donor Child Foundation, DNA testing has confirmed that a fertility specialist, Dr. Jan Karbaat, fathered 56 children, born to women who visited his clinic outside Rotterdam. Dutch authorities closed his practice in 2009, and he died in April 2017 at age 89.

An attorney for Dr. Karbaat’s family said they had no comment on the allegations and emphasized that the cases are decades old.