Science finally determines why we do it, and the #1 reason is attraction.
There's more to it than just procreation.
Researchers Cindy Meston and David Buss set out to discover why people have sex, theorizing that it's more complicated than just procreation and/or pleasure. They devised two studies to get to the bottom of it. In the first, they asked 444 people in Austin the open-ended question, “Please list all the reasons you can think of why you, or someone you have known, has engaged in sexual intercourse in the past.” From the responses, they compiled a list in which similar answers were combined, and narrowed it down to 237 reasons. They then gave 1,549 college students the list asked them to indicate how many of their previous sexual experiences could be attributed to each reason on a scale ranging from 1 ("none of my sexual experiences") to 5 ("all of my sexual experiences"). These are the 10 most common reasons for sex, according to both women and men.
So men and women have sex for mostly the same reasons. The main differences are that women ranked love and affection higher than men, who were more likely to list something purely pleasurable as a motivator. The most common reasons are all mostly positive, which makes for an interesting comparison to the least common reasons.
So Trent Reznor was pretty much on his own he sang "you get me closer to God." Like with the most common reasons, men and women responded similarly. And it's reassuring that very few people have sex to intentionally spread an STD (the average rating for the bottom 10 was around 1, meaning almost no one responded affirmatively to these reasons).
Harvard sex educator Justin Lehmiller, in his analysis of the study, writes,
Men and women are clearly more similar than different when looking at the most and least commonly reported reasons for sex. However, for the reasons that appeared in the middle of the list (i.e., things that only motivate people occasionally), a number of sex differences emerged. The nature of these differences were such that men were more likely to report sex for physical reasons (e.g., “The person was too sexy to resist”), because sex would improve their social status (e.g., “I wanted to brag to my friends about my conquests”), and because they just had an opportunity for sex (e.g., “The person was available”). In contrast, women were more likely than men to report sex for reasons such as “wanting to feel feminine” or because they “realized they were in love.”
The study offers further evidence that men and women are kind of different, but mostly similar, so let's all be cool.