On a related note, numerous fertility doctors have been caught using their own sperm to inseminate patients. Not even one or two, but numerous doctors:
Some of those who've been caught fathered children in the double digits. I can easily believe there's some with numbers in the triple digits.
Fertility treatments and sperm donation have been going on longer than people realize -- first performed in the 1880s -- and usually were not spoken about at all. Even today, on the genetic genealogy forum I frequent, it's common for parents to deny, deny, deny if asked about using donor sperm. To add to that, it seems a lot of couples struggling with infertility were fed the line "Oh, we'll mix in another man's sperm sample with the husband's, it'll help his along", which makes no sense at all from a reproductive perspective if you understand anything about conception. What do you imagine is happening, the donor's sperm pushes the husband's immobile sperm to the egg?? But it appears doctors knew that these husbands' was sterile, and by feeding them this lie they could let them believe that the baby was fathered by him and let him keep his pride (which for some men is stored in their "virility", ie sperm, for whatever reason).