Soon after Abby Dotson and her wife, Jen Gordon, had their first child, they found out a friend was pregnant. They were thrilled at the chance to give someone their baby's outgrown clothes.

But Dotson says she and her friend Lizzie Keith quickly discovered their kids would share much more than old T-shirts. Without knowing it, the couples had picked the same sperm donor—meaning their kids would be genetically related "diblings," or donor siblings.

(Christine Dong)
(Christine Dong)

"We both started crying. Our sons were going to be brothers," Dotson says. "It still gives me goose bumps just talking about it."

After the serendipitous discovery, Dotson decided to seek out her son's other diblings on an online forum called the Donor Sibling Registry (donorsiblingregistry.com). She was eventually able to find a Facebook group, started by the sperm donor's mom, for the half-siblings to connect.

In a similar quest to connect with their son Oso's diblings, local couple Chris and Erin Collins did a Google search of their donor's code name and found the Facebook group that Dotson and Keith were members of. The three families, whose kids are all half-siblings, now meet up at least once a month.

(Christine Dong)
(Christine Dong)

"We made an instant connection," Chris Collins says. "I hope our kids think this is cool and special. Many of us have chosen family—I don't talk a ton to my own family—but our sons get to have blood family."

Collins and Dotson have met the donor's mom, who lives in Seattle, and his nieces and nephews—their kids' half-cousins. They say some similar traits—like the donor's large smile—are noticeable in all of the children. When they turn 18, the diblings will have the option to meet the sperm donor.

(Christine Dong)
(Christine Dong)

According to Dotson, new families—mostly lesbian couples and single mothers—are joining the donor sibling Facebook group every month. And because the donor also sent sperm to Europe, their kids have genetic half-siblings all over the world.

"We get to watch each other's kids grow up," Dotson says of the group. "The more people who love my son, the better."

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(Christine Dong)

Click here for the full Best of Portland 2018 guide.