Arianne Cohen has learned a few things from poring over the sex diaries of 1,500 people. For starters: relationships are a lot like careers. Sure, some of us work 9 to 5—but others stay home in pajamas all day, eating crackers in bed. Second: men and women aren’t all that different. (In fact, Cohen had trouble telling their diaries apart.) Except, perhaps, when it comes to one topic: porn. Men watch it. A lot.