What's the problem?
I don't feel like spending an hour pointing out each historical inaccuracy.
There are very old claims that Hitler's grandfather was Jewish, and some evidence, including DNA, supporting them. There is no convincing evidence otherwise.
Plenty of Germans and Czechs have some Jewish Ancestry. Figuring out where and when is the hard part.
Indeed, what other explanation comes anywhere as close?
German Romantic Nationalism and the Volkisch movement? Go read the works of Wilhelm Marr, who coined the term anti-Semitic, to explain his modern, scientific, racial hatred of Jews and differentiated it from the medieval religious Judenhass (Jew Hate). Karl Leuger of the Christian Social Party was elected a few times as mayor of Vienna on a platform attacking Jews, especially those from the east. Hitler was fond of Leuger.
Sorry, my bad -- did not intend to provide a link to lunatics.
rmlew: "Plenty of Germans and Czechs have some Jewish Ancestry."
So, you agree it would not be so unusual to find that Hitler too had Jewish ancestors?
We should note again that allegations of Hitler's Jewish grandfather came early and came from people close to Hitler.
Those could just as easily claim some other scandal -- i.e., illegitimate birth, incestuous parents, etc. -- but they chose Jewish ancestry for a reason, political doubtless, but also likely that is what they knew.
rmlew: "Hitler was fond of Leuger."
Did Leuger advocate mass extermination of Jews?
I doubt it.
Hitler was in a different class, one requiring more explanation...
Finally, check out the other two sites linked above.
Hopefully you'll find them factual, fair and free of anti-Semitism.