Educator Henry Louis Gates Jr. has hosted a number of series for PBS that examine American culture and history. In "Finding Your Roots," the Harvard professor continues his quest to "get into the DNA of American culture," as he describes it. In each episode, a celebrity pair -- bound together by an intimate, and sometimes hidden, link -- wades through layers of ancestral history to uncover secrets and surprises from their family trees, sharing life-altering discoveries with viewers. The celebrities discover unknown family histories and relatives they never knew existed. By analyzing each participant's genetic code, DNA diagnosticians trace bloodlines and occasionally debunk long-held beliefs. Among the celebrities featured in the 10-part series are Kevin Bacon, Robert Downey Jr., Martha Stewart and Barbara Walters.