Valerie Bertinelli thought she knew her paternal grandfather — until she traced her ancestry and discovered that he was harboring some big secrets. The actor appeared on Season 10 of latest episode of PBS' hit series "Finding Your Roots" and made two shocking revelations while chatting with host Henry Louis Gates Jr. 

Valerie Bertinelli came on the show specifically to learn more about her dad's father, Nazzareno Bertinelli. Born in Italy, he lived with Valerie Bertinelli's family when she was growing up in the U.S., and died of an illness when she was still a girl. First, Valerie Bertinelli learned that her grandmother wasn't her grandfather's first wife. As it turns out, he first married to a woman named Domenica Cellerani back in his Italian hometown.