It was AncestryDNA’s customer-service rep who had to break the news to Catherine St Clair.
For her part, St Clair thought she was inquiring about a technical glitch. Her brother—the brother who along with three other siblings had gifted her the DNA test for her birthday—wasn’t showing up right in her family tree. It was not a glitch, the woman on the line had to explain gently, if this news can ever land gently: The man St Clair thought of as her brother only shared enough DNA with her to be a half-sibling. In fact, she didn’t match any family members on her father’s side. Her biological father must be someone else.
“I looked into a mirror and started crying,” says St Clair, now 56. “I’ve taken for granted my whole life that what I was looking at in the mirror was part my mother and part my dad. And now that half of that person I was looking at in the mirror, I didn’t know who that was.”
St Clair thought she was alone with her loss, and...