JOHNSON: It's part of who I am. NARRATOR: On "Finding Your Roots" Jeh Johnson. JOHNSON: It's the American story. NARRATOR: And Angela Davis. DAVIS: This is something I never expected to discover. NARRATOR: An unexpected family arrangement. JOHNSON: I can't undo it, I won't disavow it. NARRATOR: And DNA rocks the boat. DAVIS: No. (laughs) GATES: Your ancestors came on the Mayflower. DAVIS: No, no, no. NARRATOR: "Finding Your Roots"