The Fifty Shades trilogy has sold well more than 100 million copies worldwide, and now it has been made into a $40-million movie. Kink may be the “new normal” for hot sex, but BDSM and other fetishistic play has a long history. Moviegoers and readers who are new to kink may not be familiar with the strong set of norms and ethical guidelines in the BDSM community—and how to make sure this kind of sex is safe, consensual, and healthy.

Romance novels aside, more people might interested in kink than you'd think—a 2009 study found that both men and women prefer fantasies of being dominated, rather than dominating others. For more, see Emma Green's "Consent Isn't Enough: The Troubling Sex of Fifty Shades."

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