Ken Burns learns that his Southern ancestors include Confederate soldiers and a slave owner; Anderson Cooper learns that an ancestor on his father's side was killed by one of his slaves; and Anna Deavere Smith learns about her great-grandfather, who was a free black man and former conductor on the Underground Railroad.

Secrets encoded in their genomes challenge these guests’ ideas about their families’ histories and their identities today. This episode features Jessica Alba, Anderson Cooper, Valerie Jarrett, Governor Deval Patrick and more.