Big Sperm Families

Science, technology, and life.
Feb. 25 2009 10:58 AM

Big Sperm Families

Eight hundred years ago, if you wanted to father a swarm of children, you had to seize power, kill men, and collect a harem of women. That's what Genghis Khan did. "An astonishing 8% of males throughout the former lands of the Mongol empire carry the Y chromosome of Genghis Khan," Nicholas Wade reports in his excellent book Before the Dawn . "This amounts to a total of 16 million men, or about 0.5% of the world's total."

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William Saletan William Saletan

Will Saletan writes about politics, science, technology, and other stuff for Slate. He’s the author of Bearing Right.

Today, if you want to spread your seed around, it's a lot easier. Just make a deposit at a sperm bank .

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Thanks to the Donor Sibling Registry , a nine-year-old organization that helps genetic siblings find one another , it's increasingly possible to find out who's been fathering whom in the world of egg and sperm donation. And even when you can't find out who, you can often find out how many. Human Reproduction has just published a survey of parents connected to the registry. The parents had sought out their kids' donor siblings, i.e., kids conceived from the same donor. And guess what? "In several cases, a considerable number of donor siblings had been traced, with 11% (55) of parents who had found their child's donor siblings finding 10 or more, reaching 55 siblings in one instance."

Fifty-five kids from a single donor. Think about that: You have 54 siblings and don't even know who they are. In a town of 5,000 people, what are the chances that somebody close to you—neighbor, mail carrier, waitress, wife—is secretly a relative? And while that's the extreme case, donor reuse seems to be quite common. If 11 percent of donors are being reused 10 or more times, that's a lot of Genghis Khan action. Think of what that's doing to communities, kids' identities, and even biodiversity.

Tabitha Freeman, one of the study's authors, blames lax regulation :

More than 90 percent of parents included in the study came from the United States, where guidelines regulating the use of sperm or eggs are looser than in Britain, she added. "The study is exposing that some clinics are using the same donor for a lot of families," Freeman said. ... "Guidelines suggest this should not be the case but they are not strictly enforced" in the United States, she added.

Maybe while we're beating up on Nadya Suleman, the octuplets' mom , for bearing 14 children, we should stop to think about all the men who have been fathering carloads of kids without even knowing about it. Apparently, the clinic that impregnated Suleman used her to inflate its IVF success rate because she was a reliable producer . That's the same reason a lot of sperm donors get reused. Even if all these kids can be cared for, is there something unhealthy about pumping out child after child from the DNA of one person? Have we had enough of Genghis Khan?

 

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