Does Hitler have Jewish in his descent?

There are some rumors hinting that Hitler's grandfather was Jewish, but few Hitler historians believe that this is true, (but see below). This rumor most likely started because Hitler always tried to keep the history of his family secret, but this was most likely because there was a high incidence of insanity in his family history, not because of a Jewish ancestory in his family.

Early in his time as chancellor of Germany, Hitler did assign Joseph Goebbels to research his lineage to find out if he had any Jewish blood. Goebbels reported back that there was a 50/50 chance Hitler was 1/4 Jewish.