Jessica Biel gets a big surprise on this week's episode of Who Do You Think You Are?.
The 35-year-old actress joined the uber popular TLC series to debunk several stories of her family's history, and only ET has an exclusive sneak peek.
In the preview clip, Biel is shocked to find out that her ancestors were Jewish.
"Wow, I've never heard of this before in my family," Biel says. "That's kind of a big deal to not know about."
"That sort of changes everything," she adds.
This season, the show will also follow Julie Bowen, Courteney Cox, Jennifer Grey, Smokey Robinson, John Stamos, Noah Wyle and Liv Tyler.
Watch the exclusive clip above.
Who Do You Think You Are? airs Sunday at 10 p.m. ET/PT, 9 p.m. CT on TLC.