Why some couples have more sex

Photos: Hollywood's steamiest sex scenes
'Fifty Shades of Grey' (2015) – "Fifty Shades of Grey" came out around Valentine's Day in 2015, a perfect time for a film whose sex scenes had some blushing red. It isn't the first movie with risque scenes that had moviegoers titillated.
Hide Caption
1 of 28

Photos: Hollywood's steamiest sex scenes
'Last Tango in Paris' (1972) – Graphic sex scenes between Marlon Brando and Maria Schneider in "Last Tango in Paris" shocked the world at the time and initially earned the film an X rating as well as two Academy Award nominations.
Hide Caption
2 of 28

Photos: Hollywood's steamiest sex scenes
'Don't Look Now' (1973) – The graphic sex scenes between Donald Sutherland and Julie Christie in "Don't Look Now" resulted in an X rating at first and have fans still wondering, did they or didn't they?
Hide Caption
3 of 28

Photos: Hollywood's steamiest sex scenes
'Nine 1/2 Weeks' (1986) – "Nine 1/2 Weeks," starring Mickey Rourke and Kim Basinger, wasn't a huge commercial success, and critics didn't love it -- except maybe Roger Ebert -- but it had couples acting out that food scene.
Hide Caption
4 of 28

Photos: Hollywood's steamiest sex scenes
'The Unbearable Lightness of Being' (1988) – Daniel Day-Lewis and Lena Olin had some sexy scenes in "The Unbearable Lightness of Being."
Hide Caption
5 of 28

Photos: Hollywood's steamiest sex scenes
'Basic Instinct' (1992) – Gay activists protested "Basic Instinct," starring Michael Douglas and Sharon Stone, as they felt that the portrayal of her bisexual character was offensive.
Hide Caption
6 of 28

Photos: Hollywood's steamiest sex scenes
'The Lover' (1992) – Jane March and Tony Leung Ka Fai star as a young girl and her older lover in "The Lover."
Hide Caption
7 of 28

Photos: Hollywood's steamiest sex scenes
'Mulholland Drive' (1996) – Naomi Watts, left, and Laura Harring got hot and heavy in "Mulholland Drive."
Hide Caption
8 of 28
