Michael De Luca and Dana Brunetti, the producers behind The Social Network, were confirmed Monday as the producers of best-selling racy novel series Fifty Shades of Grey, known as "mommy porn." Readers are now speculating on whether potential casting for characters Christian Grey and Anastasia Steele will include the two Twilight stars.

But Fifty Shades of Grey author E.L. James has confirmed in an interview last week that Robert Pattinson and Kristen Stewart, stars of "Twilight: Breaking Dawn Part 2," will not be cast in the parts of billionaire Christian Grey and naïve college student Anastasia Steele.

Who does the British author want to see in the movie?

James, whose book has sold about 20 million copies worldwide, wouldn't give names but she did say she has some people in mind.

"I have about four people in mind for Ana's role and three in mind for Christian's part," said James. "I'm not telling anyone what they are because I'm not allowed to discuss the film… which is a real shame. Things are moving slowly on that [front]."

The author has given Universal Pictures and Focus Features rights to produce a movie adaptation of the book but still retains some say in who will be cast in the roles of her two characters.

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Fifty Shades of Grey follows the relationship between Christian Grey and Anastasia Steele. The book contains graphic erotic scenes that include BDSM (bondage, discipline, sadism, and masochism). It has been dubbed "mommy porn" for its sexual content and large female following.

Critics, including celebrity doctor Dr. Drew, have called the book "disturbing" and argued that it perpetuates violence against women.

In March, a Florida library banned the book but later made copies to patrons due to public demand.