The revelation about her sister caps a drama-filled time for Oprah. Just last week she opened up to CNN's Piers Morgan, about giving birth when she was 14 to a baby boy who died after two weeks.
"When I lost that baby for whom I had no connection to whatsoever, I was 14-year-old and felt nothing but ok relief," Oprah says.
Last spring, an unauthorized biography was released by author Kitty Kelley. Among the claims that Oprah doesn't believe Vernon Winfrey is her real dad.
Then World War II Veteran Norh Robinson, came forward to say he was Oprah's biological dad. Oprah dismissed the claim with disdain.
"All my new daddies are showing up," Oprah says.
This time around, Oprah wanted to reveal her family secret on her own terms.
"I wanted you to hear the truth from me," says Oprah.