And consider this: A single donation at a sperm bank can produce as many as 24 sellable vials. Whitehurst's 400 donations could have produced 9,600 vials for his clinic to sell.
He says he has 22 donor children that he knows of.
"You could have a family touch football game and have enough players for both sides," said Strassmann.
"Maybe compete with other families, too!" said Whitehurst. "It does seem crazy."
But on this long Cape Cod weekend, there was no sign anyone felt like part of a herd -- just a clear curiosity from eight half-siblings about each other -- and about their donor-father.
"Going forward, do you feel a responsibility for their lives? Strassmann asked.
"Yeah, I do," said Whitehurst. "It's sort of the responsibility I feel as an uncle. I realize I'm not their parent, right? Their parents are primarily responsible for them. But if their parents are unable to help them, then I would step in and do what I could.
"You feel love," he added. "You want to protect them. You want them to have a happy life. They've all turned out to be really quite remarkable children."
Carey Phelps now studies computer science at Stanford -- just like her donor-dad.
"I never felt like there was something missing, because I've been so lucky," she said. "I'm so wanted, and that's something that I think a lot of kids can't say for certain. And so being able to meet all of these totally different, but at the same time, very related siblings is, it's such an incredible honor for me to grow up this way."
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