Who was Adolf's grandfather?

Hansjurgen Koehler in his book, "Inside The Gestapo," states the following, of Maria Anna Schicklgruber, Adolf Hitler's grandmother,

"A little servant girl…….came to Vienna and became a domestic servant…….at the Rothschild mansion…….and Hitler’s unknown grandfather must be probably looked for in this magnificent house."

This is backed up by Walter Langer in his book, "The Mind Of Hitler," in which he states,

"Adolf’s father, Alois Hitler, was the illegitimate son of Maria Anna Schicklgruber…….Maria Anna Schicklgruber 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 home…….where Alois was born." [2]

In 1837 she was 42 years old, and still single, when her first and only child was born. She named the boy Alois. Maser notes that she refused to reveal who the child's father was, so the priest baptized him Alois Schicklgruber and entered "illegitimate" in place of the father's name on the baptismal register.

http://en.wikipedia.org/wiki/Maria_Schicklgruber