There's been a lot of news of late about the girl who discovered that she was fathered by a worker at an infertility clinic, who seems to have substituted his own semen for that of her mother's husband during the treatment process. It now appears that the worker may have fathered hundreds of children in that way, although the true number may never be known.
In this case, the sperm donor did so without authorization - but even when a legitimate sperm donor is used, there can be complications. Witness the scandal in Scandinavian countries when a Danish sperm donor was proved to carry a genetic disease. By the time this was discovered, his sperm had been used to father dozens of children, of whom some have since been found to have inherited the disease. Another example is that of the sperm donor who fathered about 150 children, none of whose parents are aware of the others. As the New York Times pointed out:
... there is growing concern among parents, donors and medical experts about potential negative consequences of having so many children fathered by the same donors, including the possibility that genes for rare diseases could be spread more widely through the population. Some experts are even calling attention to the increased odds of accidental incest between half sisters and half brothers, who often live close to one another.
There's more at the link.
Now CNN reports on another case.
What are the chances that two California teens would meet online in a roommate hunt, cross the country to attend Louisiana's Tulane University and learn a semester later they were half-sisters, the daughters of the same Colombian sperm donor?
Emily Nappi, 18, of San Francisco, and Mikayla Stern-Ellis, 19, of San Diego, learned exactly that January 7, when, acting on a suspicion they'd joked about since Father's Day, the women asked their mothers to hunt down their sperm donor numbers from the Los Angeles-based Calfornia Cryobank.
Stern-Ellis was in a doctor's office. She had asked her mother to send her the number. Nappi had done the same.
"They both text me at the same time, and it was the same number," Stern-Ellis said. "I was just staring at my phone. I didn't know what to do. I think the only way to describe it is mind-blowing."
Now that they know they're sisters, it all makes sense. They have the same build and are able to share clothes -- but, sadly, not shoes -- and they're science majors, with Stern-Ellis focusing on animals, Nappi on psychology.
They both sleep-talk and sleepwalk, reported The Advocate in Baton Rouge, and during a Black Friday shopping trip over Thanksgiving break, they independently purchased the same sweater.
Again, more at the link.
I know there have been several cases (click these four links for examples) where engaged or married couples have found that they're half- or full brother and sister. The trauma of discovering that their marriage is illegitimate in the eyes of the state and (usually) their church is heart-breaking. Precisely the same thing may happen when the children of the same sperm donor get married. I'd say it's only a matter of time . . .