In her new memoir, Maureen McCormick reveals intimate details about her secret life of binging on cocaine, trading sex for drugs and dating her TV sibling.

In "Here's the Story: Surviving Marcia Brady and Finding My True Voice," she also writes about her romances with Michael Jackson and Steve Martin. She delves into her relationship with Barry Williams, who played Greg Brady.

The affair intensified while the The Brady Bunch filmed episodes in Hawaii.

"We couldn't hold back any longer," she writes in the book published by William Morrow. "It was our first kiss, and it was long, passionate and deep. It was wonderful, too, though as we continued to kiss and press against each other so closely that we could feel each other's body heat, a part of me — a tiny part, admittedly — said to myself, `Oh my God! I'm kissing my brother. What am I doing?'"

McCormick's drug addiction and depression fueled her downward spiral as she unsuccessfully tried to reconcile her real life with the one she had portrayed on TV.

In the memoir, she writes about cocaine binges and parties at the Playboy Mansion and the home of Sammy Davis Jr., an unwanted pregnancy and trading sex for drugs.

The book hits stores on Tuesday.

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