Hugh Hefner's family foursome

Hugh Hefner, founder of Playboy magazine, twirls a napkin during a performance by Dr. John and the Lower 911 at the 30th annual Playboy Jazz Festival at the Hollywood Bowl in Hollywood, California June 14, 2008.[Agencies]

Hugh Hefner once had a foursome with his wife, brother and sister-in-law. The Playboy founder is no stranger to sexual experimentation, and had no qualms about showing off his prowess to brother Keith and his sister-in-law Rae, author Steven Watts claims in new book 'Mr. Playboy: Hugh Hefner and the American Dream'.

In the book, Watts writes: "A foursome did happen with his brother, Keith, and his wife, Rae, one evening. But while Millie, Hugh's first wife, ultimately backed out of having sex with Keith, Hugh slept with his sister-in-law." Watts also alleges Hugh - who currently lives with three girlfriends at the Playboy mansion in Los Angeles - once had homosexual sex.

He continues: "Hefner's thirst for sexual experience became so strong that he even had a one-time homosexual experience. One evening in downtown Chicago he was propositioned and he thought, 'What the hell!' As far as I know, the guy just gave him oral sex." Hugh, 82, gave Watts unlimited access to his personal documents, and insists the tome is "the most authoritative book ever written about me - it's all essentially true." The book is set for release in the US in October.