Every human being is born with the knowledge of both good and evil. Hatred is all around us. We learn it at a very young age from different TV shows, music, and the people around us. Society has a way of tell us what or who to hate because it is the "right" thing. But it is also the will of the human to either accept or reject the hatred shown to us. We can choose to hate something or someone, or we can stay away from whatever it is we might hate to keep us from having those feelings.
When YOU made a conscious decision to do so . And it will not stop until YOU decide it is wrong and rectify YOUR way of thinking and attitude towards others who differs from you . Hate is a luxury we cannot afford . Get over it before it devours you !
Let me treat this as a philosophical question rather than a literal one. People learn to hate when they see hateful things on TV, hear hateful things from other people, or read them in books. If we aren't aware of angry thoughts in our own mind and correct them, they will often turn to hate. It's an individual journey from love to hate, one that you can control. Just because an angry or hateful thought comes to you for ownership, doesn't mean you have to open the door and let it in. Correct it with self-talk, "I don't have to hate anyone. Hatred doesn't accomplish anything positive. I want my thoughts to be a calm, peaceful, loving place, so I'm not going to allow anger or hateful thoughts in." Good luck.