The dilemma of donor siblings: 150 brothers and sisters, maybe more...

(thinkstock photos)(thinkstock photos)Cynthia Daily's family is growing by the minute. To date, her 7-year-old has about 150 half-siblings, all sired by the same sperm donor. "It's wild when we see them all together - they all look alike," Daily told The New York Times, in an article probing a new donor family phenomenon.

A perfect storm of overused sperm donors, unregulated practices and social networking tools, has created a new concept of family and with it, new problems.

Sperm banks are relying on the same popular donors to impregnate multiple women in nearby areas. The result is a growing number of half-siblings, and an equally blossoming fear in donor kids that anyone could be their relative.

"When I was dating, I would keep in the back of my mind, could he be a half brother," wrote a 30-year-old female surveyed in a Cambridge University, Centre for Family Research study on donor kids. That same study, found that because "some sibling groups are concentrated in specific areas unknowingly meeting a donor sibling is a genuine possibility." In other words, her fears were justified.

Currently, there are no legal limitations in the U.S. as to how many births one single donor can produce. Sperm banks are a business, and donors that look particularly attractive on paper drive the market. That means one man's services could lead to 150 kids or even more, as was the case with Dr. Kirk Maxey, who may have fathered as many as 400 children during his tenure in the '80s as a prolific donor.

"That is what I think is the problem with total anonymity," Maxey, now an advocate for stricter donor regulations,
told Nightline in 2006. "It's that I have a son that lives in the area and most of the patients came from a 100- or 150-mile radius of the area. If you do math, again, there may be 100 young women that are basically my son's age that are his half-siblings. I have to tell him there is an awful lot of your brothers and sisters that you don't know and I don't know."

Though documented cases of accidental incest are rare, the fear among donor kids appears to be widespread. One mom told the Times she made her teenage daughter memorize her donor dad's "number", as he's known to the family, to check against any other donor child she may want to date. "She's been in school with numerous kids who were born through donors," said the unidentified mother. "She's had crushes on boys who are donor children. It's become part of sex education."
In 10 years, the question, "What's your dad's number" could end up replacing "have you been tested?" as the safe-sex script.

The fear of unknown lurking siblings is mediated by the benefits of finding long-lost family. Thousands of siblings and their parents have connected on the
Donor Sibling Registry, a site that helps donor families create a tree, that's sometimes larger than they anticipated. Some have forged friendships, unearthed crucial medical histories and even formed new family units as a result.

''It has become like a common occurrence and I don't expect any of the meetings to go badly, because it is like we have known each other all our lives even though we did not grow up together," wrote a 16-year-old male in the Cambridge survey, after meeting multiple donor siblings through the Registry.

Some pockets of donor families are so close in proximity, they end up meeting by chance. Robin Anderson was at a party when she met a woman named Maren, who shared a lot in common with her. Their children had the same father, donor 48QAH (6'4, 190 pounds, physician with interest in pediatrics). Now both families live 10 minutes apart, and the children are being raised as siblings. But there are more where they came from. 48QAH was a popular donor.

The unprecedented, Sci-fi-worthy problem, is calling attention to current donor laws or lack thereof. Advocates of limiting the amount sperm donations one man can make, point to the U.K, which already mandates no more than 10 kids per sperm donor. But if laws don't change, sperm banks might need to start regulating themselves. With less guaranteed anonymity than ever before (thank you Internet), the potential for a massive brood isn't exactly enticing to prospective studs.

The Times found one "super-dad" responsible for producing 70 offspring. Now he keeps track of his progeny with the help of an Excel spreadsheet. Practical, maybe, but it doesn't solve a bigger problem. How do those 70 siblings keep track of each other?

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