Enlarge / Ignore the resemblance. (credit: Getty | Peter Dazeley)

Genetic searches on 23andMe and similar ancestry sites have identified three dozen half siblings with the same biological father—an Indianapolis-area fertility doctor who assured women decades ago that he was using sperm from either their husbands or from anonymous donors that matched certain criteria.

The fecund doctor, Donald Cline, has since admitted to lying to patients and using his own sperm to inseminate them. It is still unclear just how many times he used his own sperm. But court documents state that he admitted to one of his biological daughters, Jacoba Ballard, that he did so around 50 times during the 1970s and 1980s, according to a report by the Associated Press.

Last week, Cline surrendered his medical license to the Indiana Medical Licensing board, which also barred the 79-year-old from ever applying for a license again in the state.