Alois's maternal grandmother, Theresia Schicklgruber, married and had children with both Johannes Schicklgruber (1764-1847) and his brother Josef Schicklgruber (1757-????). On top of that, Theresia (whose maiden name was Pfeißinger) and the Schicklgrubers shared a few common ancestors. For instance, Josef and Johannes' grandfather, Mathias Silip, was the brother of Ursula Silip (Theresia's great-grandmother).