Patience

Patience is a learned behavior. We're not born with it. A toddler usually exhibits a lack of patience when they don't get their way. They pout and fold their arms to display their displeasure with your decision. As adults we often do the same thing when we don't get our way.
This is displayed as passive aggressive or even aggressive behavior. We pout and fold our arms.
I would propose that most of the world's conflicts have their root cause in a lack of patience. Think about it. When someone doesn't do something when you want it or they do something that you didn't want them to do you pout. You react by doing something to annoy them.
On a large scale wars have started this way and on a small scale it's why there's divorce or friendships dissolve.