Marcia! Marcia! Who… oops…What did you do?

“Brady Bunch” star Maureen McCormick – who played the TV family’s oldest girl Marcia Brady – will reveal in a new tell-all book how she had a steamy on-set sexual relationship with the co-star who played her younger sister Jan.The book, titled “Here’s the Story,” will detail how a small crush blossomed into a romantic and physically intimate relationship between McCormick and Eve Plumb, according to published reports. Due out next year on HarperCollins imprint William Morrow, the bombshell biography will also touch on topics such as McCormick’s battles with bulimia, cocaine addiction and depression.

But what will likely shock most fans of the 1970s hit TV series are the details of the budding love affair between the two co-stars who played the highly competitive sisters. It’s not the first time salacious details of behind-the-scenes sex have emerged in the years since the campy classic went off the air. In 1992, co-star Barry Williams, who played Greg Brady, wrote in his tell-all tome, “Growing Up Brady,” how he dated not only his on-screen mom, Florence Henderson, but engaged in several romps with McCormick as well.

And in 1997, McCormick hinted at a lesbian tryst between her and Plumb when she told a Los Angeles radio host about the crush she developed for Plumb while the two worked closely on the smash series that ran from 1969-1974. “We had really good times together,” she playfully said at the time. When asked if that meant the two had been “pattycake close or Ellen DeGeneres close,” McCormick coyly revealed the two had swapped spit. “Yeah, we kissed,” she said. Her publicist later clarified that she meant simply on the cheek.

But all the while, McCormick – like many of her young co-stars – was under serious emotional stress trying to balance her TV fame with the strains of being a teenager. Source