Alice Collins Plebuch had a surprise when she took an Ancestry.com test, the Washington Post reports. She was expecting to learn that she was of mostly Irish descent, but as the Post notes, Plebuch learned she was of half Irish and half European Jewish ancestry.
Some testing companies, though not all, try to prepare customers for unexpected findings, such as learning their dad isn't their dad. In 2014, 23andMe reported that 7,000 customers learned of unexpected paternity or of unknown siblings, the Post says.
"You find out that a lot of things are not as they seem, and a lot of families are much more complex than you assume," genetic genealogist CeCe Moore tells the Post.
After dismissing their unexpected finding as a lab error, Plebuch and her sister sought re-testing — and got the same results. While this indicated they were full siblings and that Plebuch likely wasn't adopted, nor the product of an affair, it didn't give the sisters an explanation. But when their brother underwent testing, they noticed that his X chromosome lacked Jewish ancestry, indicating the mystery was on their father's side, the Post says.
The siblings set off to trace their paternal blood relatives. Eventually, after convincing strangers to undergo testing and share results, digging through records in the US and Ireland, and consulting a forensic artist, someone suggested to them to look at other babies born around the same time as their dad in the same hospital —eventually, the Post reports, they found that their dad and another baby had been switched in 1913.