Actress Valerie Bertinelli got a bit of a surprise this week when it was revealed that her grandmother was born out of wedlock.

The secret was revealed when Bertinelli appeared on Who Do You Think You Are?, a series in its fifth season on cable channel TLC. Who Do You Think You Are? is an American remake of a British series that attempts to make genealogy compelling to a mass audience. The series takes celebrities on a tour of their past, uncovering their ancestors with the help of genealogists. Past celebrities who have appeared on Who Do You Think You Are? include Susan Sarandon, Gwyneth Paltrow, Martin Sheen, Zooey Deschanel, Cindy Crawford, and Steve Buscemi.

During Bertinelli’s episode the actress traveled from Scranton, Pennsylvania to Torino, Italy to London in search of her roots. The biggest surprise she uncovered may seem like a humorous detail in a modern context, but is something that may have been scandalous nearly a century ago.

What she discovered was undeniable proof that her great-grandmother was guilty of fornication. Documents uncovered on the show indicate that her grandmother was born in April of 1908. That is two years before her great-grandmother was married in 1910. It was revealed that Bertinelli’s great-grandmother and great-grandfather claimed Bertinelli’s grandmother as their legitimate daughter when they wed.

The Long Island University history professor that helped Bertinelli uncover the scandal explained that money may have been a factor, stating that a proper church wedding would have been expensive during the early 20th century and that a dowry payment may also have been a hindrance to marriage.

Bertinelli is best known for her role as Barbara Cooper in the long-running sitcom One Day at a Time. She is currently starring in the TV Land series Hot in Cleveland.

Other celebrities already featured in this year’s season of Who Do You Think You Are? include actress Rachel McAdams and Cynthia Nixon of Sex and the City fame. Kelsey Grammer and Lauren Graham will appear in this season’s final two episodes later this month.

Image via Angela George/Wikimedia Commons