Children is very easy to absorb the knowledge from the parents and outsiders. That's includes the love and hatred comes from all the sources and directions.
The inability to digest such information would result the hatred rooted in the heart since young age.
Hatred is as powerful as Love. It consists of equally strength to destroy and to sustain any kind of closest relationship that you have.
From the movie, both are extremely practicing their skill, one is to revenge and the other is to save and to protect. However, both situations have proven that when your beloved dies, it tremendously hurting you as you are closed to them.
I do believe some hatred couldn't be solve with just talks and talks, but with a consistent actions that to proof, love is all around with us all the time. Love is indeed needed a longer time to build than the hatred.
The hatred will exist when the time you feel millions of reason to be evil, and only few reasons to be good or nothing to be a good person at all. Have you come across with this in real life?