Theory of Bullying Behavior.

Are there people in the world that you know incite some loathing that you can not place a finger on?  That person that on sight everyone seems to hate and would rather commit murder than actually welcome their presence.  I have somehow been thinking about this and it was questioned that people are bullied no matter what.  Some people no matter how they act, no matter what their class or status within society will be bullied.  Why is this?

Could the reason for some bullying be on a genetic level?  That people instinctivly hate certain people with a particular genetic make-up?  A particular marker that on a level people sense and hate on instinct alone?  If so, could this be treated with gene therapy and create something closer to a utopia?

Some bullying does come from social standings, physical appearence and personal skills.  One reasoning, at least in my thinking along this vein is that more nerds are bullied because of the lack of social interaction and without that interaction start to persue individual interests, being an outcast they find escape in books, videos or games.  Thus, a nerd. 

Would a genetic defect be plausible as a source of bullying?  Is such a defect indicative of another possible problem that makes a person less attractive as a mate or as a procreator? 

I’d like to know opinions of this little ‘theory’.