Liza White still recalls the day she first saw Henry's photo. The toddler looked just like her daughter, Morgen.
"I remember crying and looking at his face and saying, 'Oh my God! It's Morgen, it's a boy version of Morgen!' "
Henry lived on the other side of the United States and had a mother Ms. White had never met. But he was Morgen's half-sibling.
Ms. White, a single mother by choice who lives in Seattle, used a sperm donor to conceive her daughter, now five years old. Although Morgen is technically an only child, she actually has six half-siblings - all born thanks to the same sperm donor, Northwest Andrology and Cryobank Inc.'s donor No. 893.
Theirs is a new type of extended family unit, one that stretches across continents and conventions into uncharted human territory. "There aren't words to describe what we are to each other," said Amy Andrews, Henry's mother, who lives in Washington.
Some of the women say they feel sort of like sisters. They feel the same familial bond to the children. "I could take any of these kids in and just raise them as my own," Ms. Andrews said.
The six families and seven kids are spread out from Washington state to Washington, D.C. Six of them were born within a half-year of each other and are now in kindergarten; the seventh is a younger full sibling to No. 6. The mothers found each other online when their children were toddlers, after signing on to a website called DonorSiblingRegistry.com.
On DSR, people who want to find siblings or donors can identify themselves by sperm bank and donor number, and look for anyone else with the same identification. The website has about 9,000 members and about 4,000 matches have been made.
Canada's Assisted Human Reproduction Act, enacted in 2004, called for a national registry, but none has been established.
Since the mid-1980s, most sperm donors have been identified by number. So if you can find someone who shares that number, you can be reasonably sure they're related. And, with the Internet and sites such as the DSR, finding a mutual donor is easier than ever.
This group's first connection was made between Ms. Andrews and Kathy Duke, who lives in Texas but is originally from Burlington, Ont. For a short while they were the only two. "Then all of a sudden people kept popping up," Ms. Duke recalled.
Within a couple of weeks, there were four children involved, then five, then six - and she wondered how many others were out there. "I did get worried," Ms. Duke admitted. "Then it stopped." The donor had retired.
For four years, the mothers have exchanged e-mails every six months or so, updating each other on their children's health, development and interests.
There are notable similarities. Many of the children had trouble with their ears when they were young, and mild asthma. After a doctor suggested to Ms. White that Morgen have her adenoids removed, she asked the others and found out that five of the other six children also had tonsil or adenoid problems.
Two of the boys, Henry and Ethan, resemble each other so strongly they can't tell themselves apart in photos. "Ethan still points to a picture of Henry and says that's him as a baby," Ms. Duke said.
In the summer of 2006, five of the six families met in person for a three-day weekend. "It was a little strange," Ms. White said, "like a family gathering with people you've never met."
The only things the parents seemed to have in common was that they were lesbian and they'd all chosen the same donor.
Some of the women are rural, some urban. Some are in relationships, some single. Ms. White is a vegetarian, while another mother simply couldn't fathom why anyone would choose not to eat meat. They range from agnostic to deeply religious.
Still, the weekend went smoothly. The kids had a special energy together, said Ms. White: "It was like they were all humming and vibrating at the same frequency."
The children aren't entirely clear about who these "special friends" are, although they have all been vaguely told about their conception. Ms. White created a book for her daughter, Morgen, which explains a bit about how they are related, saying that their mommies all needed help to have them and that the same person provided it.
The man who spawned this clan remains unknown. When they chose him, the women knew he had wavy hair and blue eyes, was outgoing and athletic, and had two children of his own.
The women have chosen what's known as an "identity-release" donor, which means that when the children turn 18, they will be informed of his name and last known contact details.
Some of the mothers said it felt much more important to form this peer group than to seek out a connection with the donor.
"I didn't want Walker to be the only one out there," said Sara, who lives in Kansas City, Mo., and asked to be identified only by her first name.
"I was adopted, and even though I had the best parents in the world, I still had the urge to know who my biological family was."
Ms. White said the donor is "the missing player in all this."
"It's like he's a part of this circle but he hasn't shown up yet," she said.