Actress Mackenzie Phillips. (Photo:Reuters)

Actress Mackenzie Phillips revealed that she had a sexual relationship with her father, John Phillips, the founder of The Mamas and the Papas band of the 1960's.

The secret unveiled after 31 years is told in her new memoir High on Arrival which hits stores this week but she also talked openly about it to Oprah in an episode of the Oprah Winfrey Show airing today. She writes in her book that her father had sex with her on the night before she was to marry Jeff Sessler, when she was 19.

My father was not a man with boundaries. He was full of love, and he was sick with drugs. I woke up that night from a blackout to find myself having sex with my own father, Mackenzie writes in her book, according to CBS News today.

The actress also claims that her father, who died in 2001, introduced her to cocaine. Phillips has struggled with drugs and last year she was arrested for cocaine and heroin possession at the Los Angeles airport while on her way to New York.

Watch the show's promo below: