Was Hitler of a Jewish descent ?

Walter Langer wrote in his book The Mind of Adolf Hitler that it was his theory that Hitler was himself one-quarter Jewish and the grandson of a Rothschild. He wrote: There is a great deal of confusion in studying Hitler's family tree.
Adolf's father, Alois Hitler, was the illegitimate son of Maria Anna Schicklgruber. It was generally supposed that the father of Alois Hitler was Johann Georg Hiedler...
Alois, however, was not legitimized, and he bore his mother's name until he was forty years of age when he changed it to Hitler.A peculiar series of events, prior to Hitler's birth, furnishes plenty of food for speculation.
There are some people who seriously doubt that Johann Georg Hiedler was the father of Alois. Thyssen and Koehler, for example, claim that Chancellor Dolfuss (the Chancellor of Austria) had ordered the Austrian police to conduct a thorough investigation into the Hitler family. As a result of this investigation a secret document was prepared that proved Maria Anna Shicklgruber was living in Vienna at the time she conceived.
At that time she was employed as a servant in the home of Baron Rothschild. As soon as the family discovered her pregnancy she was sent back to her home in Spital where Alois was born.
In a postscript in Langer's book, Robert G.L. Waite adds this comment.
But even when Langer is mistaken and his guesses prove incorrect, he is often on the right track.
Consider his hint that Hitler's grandfather might have been a Jew. There is no reason to believe the unlikely story told by Langer's informant that Hitler's grandmother Maria Anna Schickelgruber, a peasant woman in her forties from the Waldvietral of rural Austria, had had an intimate liaison with a Baron Rothschild in Vienna.
But Hitler had worried that he might be blackmailed over a Jewish grandfather and ordered his private lawyer, Hans Frank, to investigate his paternal lineage.
Frank did so and told the Fuehrer that his grandmother had become pregnant while working as a domestic servant in a Jewish household in Graz.
The facts of this matter are in dispute — and a very lengthy dispute it has been.
The point of overriding psychological and historical importance is not whether it is true that Hitler had a Jewish grandfather, but whether he believed that it might be true.
He did so believe and the fact shaped both his personality and his public policy.
It is possible that Hitler discovered his Jewish background and his relation to the Rothschilds, and aware of their enormous power to make or break European governments, re-established contact with the family. 
This would partially explain the enormous support he received from the international banking fraternity, closely entwined with the Rothschild family, as he rose to power.
One thing is certain, however. Hitler started World War II by moving into Austria first. It has been theorized that he moved into this country for two reasons. First, he wanted to silence Dolfuss who Hitler believed knew that he was a descendant of the Rothschilds, and secondly, he wished to remove all traces of his ancestry from the Austrian records.

The Unseen Hand