Why do you have sex?

Many scientists assume people have sex for simple and straightforward reasons such as to experience sexual pleasure or to reproduce, but new research at The University of Texas at Austin reveals hundreds of varied and complex motivations that range from the spiritual to the vengeful.
After conducting one of the most comprehensive studies on why people have sex, psychology researchers David Buss and Cindy Meston uncovered 237 motivations, which appear in the August issue of Archives of Sexual Behavior.
People’s motivations ranged from the mundane (”I was bored”) to the spiritual (”I wanted to feel closer to God”) and from the altruistic (”I wanted the person to feel good about himself/herself”) to the manipulative (”I wanted to get a promotion”).
Some said they had sex to feel powerful, others to debase themselves. Some wanted to impress their friends, others to harm their enemies (”I wanted to break up a rival’s relationship”).
Physical reasons such as to reduce stress (”It seemed like good exercise”), feel pleasure (”It’s exciting”), improve or expand experiences (”I was curious about sex”), and the physical desirability of their partner (”The person was a good dancer”).
Goal-based reasons, including utilitarian or practical considerations (”I wanted to have a baby”), social status (”I wanted to be popular”) and revenge (”I wanted to give someone else a sexually transmitted disease”).
Emotional reasons such as love and commitment (”I wanted to feel connected”) and expression (”I wanted to say ‘thank you’”).
Insecurity-based reasons, including self-esteem (”I wanted the attention”), a feeling of duty or pressure (”My partner kept insisting”) and to guard a mate (”I wanted to keep my partner from straying”).
So again I ask you,why do you have sex?