TLC's Emmy Award-winning series, WHO DO YOU THINK YOU ARE? is celebrating its tenth anniversary with the return of a new season on Monday, May 21st at 9/8c featuring a new group of celebrities who are eager to explore their family roots. This season, six all-new, hour-long episodes will dare to reveal surprising family histories of some the country's most prominent public figures. With the help of Ancestry.com and historical documents, these stars embark on exciting missions to discover their own heritage. After years of passed down family legends, it is finally time to set the record straight for their families and themselves and uncover the truth behind their ancestry. For some, that may mean tracing back several generations to distinct moments in world history.