Some sperm donors are quite robust in their generosity. After all, it’s quick and easy for a man to donate his reproductive material. If he has desirable genes, he can sire a gaggle of children and not have to worry about taking care of them. This occurred recently in Hollywood, where a man fathered offspring for nearly two dozen different mothers, many living in the same vicinity. Some of the moms, in keeping with the laid-back ethos of California, decided to get together with each other, and their kids, and go on holiday.

According to a story in the Hollywood Reporter ┬áit all began when Sarah Fain, a TV writer-producer for The Shield and The Vampire Diaries, received donor sperm and birthed a child named Violet. When Violet was a toddler, Fain took her to a music class. Another mom appeared with a boy about Violet’s age. The boy looked awfully familiar.

So Fain checked her Facebook group of 15 families who had used the same “open” sperm donor — i.e., the identity of the donor and recipient are known to each other, which is a growing trend in California. It turned out the boy in music class is Violet’s half-brother, one of many other half-siblings who live in close proximity.

“They’re my family,” Fain told the Hollywood Reporter, noting that they now all get together for dinner every Sunday. The group even rented a vacation home, where the moms and a dozen toddler half-siblings stayed. “It’s one of those things that feels incredibly bizarre for half an hour,” Fain explained. “Then it feels totally normal.”

Bill Rogers is a Toronto lawyer and blogger covering family law and fertility law issues, and a columnist for the Medical Post covering the law of malpractice.