Why People Do What They Do

Ever have those moments where you hear or read about something that you already know, but the way the thing is presented finally crystallizes it for you?

People follow their strongest impulses. It?s pure luck of the genetic and environmental draw if your strongest impulses are socially acceptable.

This crystallized, for me, why people do what they do. It's something I already realized in a more nebulous, hand-waving way but now the concept is firmly locked in my head in a much shorter, more succinct way.