Danielle Teuscher's 5-year-old daughter Zoe is one of thousands of children conceived with sperm from an anonymous donor. When Teuscher wanted to know more about her daughter's ancestry and possible health issues, she and other family members decided to get DNA tests from 23andMe and added one for Zoe. What turned up appeared to be one of the anonymous donor's immediate relatives. She was shocked. The donated sperm had come from Northwest Cryobank, which offers donors anonymity, but Teuscher said the apparent relative she found on 23andMe listed themselves as open to messaging. "I said 'I don't want to cross...