I think the "Hitler was part Jewish" thing is something some people would like to find out.
But I don't think it would change a lot. We don't need facts like this, true or untrue to know that he was wrong.
But to think about the early biography of Hitler reminds on something that does not fit if you compare Voldemort with Hitler.
Before Hitler started his "political career" he was a real looser.
He wanted to be an artist, a painter and tryed to get a place at the academy in vienna. But he failed. I is said that he never came over this.
Voldemort is not described as a looser. He was the best in everything he did. (even in beeing evil)