By all accounts, Dr. Kirk Maxey of southeast Michigan appears to be a regular dad, attending his 12-year-old son's soccer games, leading rock-climbing excursions or grabbing some ice cream. But Maxey also happens to be one of the country's most prolific sperm donors, fathering approximately 400 children after donating his semen twice a week between 1980 and 1994. He's now pushing for stricter sperm bank regulation and mapping his genome online to inform his offspring.

George Church of Harvard's Personal Genome Project asked Maxey to be one of the first ten volunteers to have his genome mapped.

"Due to fertility-clinic policies, many donor offspring don't have complete access to medical history, and having their genome sequence might catch some predictable and actionable gene," Church told Newsweek . "Making Maxey's genome available could help people who actually want to find their father, or mothers who feel the current regulation of sperm banks is inadequate. Rather than merely beguiling with descriptions of tall, blue-eyed professionals as sperm donors, the clinics should also be checking for potential genetic tragedies."

Fortunately, Maxey seems healthy, with just a 1.9 percent increased risk for coronary heart disease, a reduced risk for Alzheimer's and a reduced risk of baldness. However, there are other potential problems, as Maxey mentioned in a 2006 interview with ABC News :

"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."

Maxey told Newsweek that the current sperm donation system must be government-regulated. The FDA's guidelines indicate that donated sperm can't have a "relevant communicable disease agent or disease," but there is no limit on how many donations can be made by one person. Individual sperm banks can choose a maximum amount, typically between 15 and 25 vials.

Maxey said, "Statutory rules for genetics tests on donors should be part of FDA guidelines, which should also require that sperm banks follow up on the children to make sure they are healthy. All I'm really advocating for is the absolute informed consent for the mothers."