Or maybe I watched too much Sci-Fi in my youth.
Anything like blood, sweat, semen, or even breast milk that is a a blood product would contain the donor’s DNA. A woman with a male donor would actually show up as a male (XY chromosomes) in a DNA test. Might be a great way to commit the perfect crime.
Like in the recent, well filmed and crazy “new frankenstein” type sci fi of perpetual youth, connected to long lived eels (kid you not) and drinking their “water”.
Only came to see it because of the actor who played Banastre Tarleton in Mel Gibson’s “The Patriot” (and was superior as Marshal Kryuchkov in “The Death of Stalin” .
The movie is like a “teched up” modern version of the “story” of a “doktor” at a bavarian “spa” where no one gets old, but they can’t leave, for their serum “addiction” and role in producing more at some point. Pretty entertaining with enough bourbon on board.
“A Cure for Wellness”: https://en.wikipedia.org/wiki/A_Cure_for_Wellness