Nobody is born with hatred.  It's through repeated mistreatment which hatred arises, or at the very least the perception of mistreatment.  It's the natural response towards detriments to one's own existence; I hate these flies that always buzz right by my fucking ear when I'm trying to concentrate, I hate all the traffic on the road when I'm trying to get home from a long day, I hate it when people lie to me esp. when I know they're lying to me, I hate it when I stub my toe.  I could explain why I feel the way I do about these things--and the list is quite extensive--but it should be evident as to how these things can be a detriment to my existence, even if only marginally.

I think the allegory of the two wolves is a very two-dimensional understanding of relationship ethics.  You are going to experience a wide range of emotions in your life and they are all there to help direct your behavior towards something productive for yourself, assuming you don't try to discard them under the false pretense that certain emotions are always inappropriate to hold.  If you hate something, you would do better to understand why you hate, rather than throwing the emotion away under the pretense that it's replacing another emotion you could be having.  Through understanding the hatred, you learn more about yourself and your own needs, you better understand what you want out of this life.  Hatred repels you and love attracts you: both are necessary to guide your behavior, two faces of a coin.