Hitler wasn't half Jewish. Himmller was expected to have an affair before the Nazi with a Jew and even bigger, Hendrich was suspected to be a Jew as having a grandmother or something who was Jewish.
This myth has legs but is wrong, however, one aspect why Hitler might have had such detest for the Jews is that his mother who died when he young (not very young) died and she had a Jewish doctor.
@Justin Curtis55: Hiter loved his mother but hated his father, due to his violent beatings and drinking.
Hope this helps you, framistan.