We've got an exclusive sneak peek (above) at Parsons' big revelation about his six-time great-grandfather, who he discovers was made a premiere architect first class to the King of France in 1787, just two years before the start of the French Revolution -- all while visiting a French church that was considered one of his ancestor's architectural masterpieces.
Parsons decided to research the paternal side of his family in a tribute to his late father, and that took him on a journey to Louisiana and then France, where he got to see the beautiful work of his forefathers firsthand. "Who Do You Think You Are?" will return with 10 new episodes in 2014.
Watch above and tell us: Which was your favorite celebrity revelation on "Who Do You Think You Are?" this season?
The season finale of "Who Do You Think You Are?" airs Tues., Sept. 10 at 9 p.m. ET on TLC.