People say that men and women have different sex drives. This is actually not true.. not true in the slightest. Sometimes it may seem that way, and has stereotypes as such, but in truth, they're about the same. The largest difference in sexual drive comes from hormone differences. Both genders' sexual hormones are designed to be at their optimum levels for maximum arousal at different ages - males in late adolescence/late teens, and females at around 30. They're both based on getting the best use.. as nature sees it.. of the sexual organs. Men generally begin a slow decrease in energy/stamina/youngness (can't think of another word meaning that natural ability of a part of the body lowers with the progression of age.. like old joints).. and women near the end of their prime for a successful pregnancy.
Aside from those however... people don't really tend to think about it objectively too much it seems.. especially with all the stereotypes floating around. Sex is actually an addiction. Of course your hormones and genetics will perk your interest, but in the process of experiencing pleasure, the sensation is registered in a portion of the brain that deals with addiction as well. Basically.. this renders sex as being a self-inducing addiction brought on by nature. Since people addict themselves.. like any other addiction.. the drive will then be as strong as the addiction itself... or really as far as they have addicted themselves to sex. ^_^