Dominant Behavior

If you watch enough nature shows you get a general idea of how evolution has resulted in the survival and continuance of the strongest individuals.  They are able to dominate their rivals and generally attract females.

So in most species you see males either fight or display their skills and the females are predisposed to pick the most dominant males.

There would be no reason to believe that humans evolved any differently and whether we want to admit it or not most of us behave the same ways instinctively.  We can certainly make different choices and it might also be true that in today's world, physical attributes may not be the most significant for success, but our instincts are formed based on a very long evolutionary past.  In fact to some extent this instinctive behavior may be the basis for much of the bullying that goes on.

None of this excuses bad behavior, we are able to make decisions based on moral and legal rules, but it is an underlying factor in how we behave.  It leads to the alpha's in a group exerting a certain dominance and perhaps trying to display that dominance to the rest of the group.

This behavior may even be done at the subconscious level, where our instincts still rule, and lead to behavior that may make others uncomfortable.

It is not something that can be changed easily, it is too embedded, but it can be controlled.  Still it will still exhibit itself in certain situations.

In most situations dominant personalities will emerge and sometimes they will make other uncomfortable.  What the proper reaction is to this obviously varies based on the individual circumstances, but it isn't just going to stop, its too ingrained.