"you gotta have a license to drive a car, a license to own a gun, heck, you gotta have to have license to catch a fish! But any butt reamin' ->-bleeped-<- can be a father" - Todd Higgins, Parenthood 1989
Propogation of the species is the main driver behind human behavior, at least if you believe Charles Darwin. In nature's eyes making more humans is good. Killing your fellow humans, decreasing their number is bad.
Any questions?