Answer
To honor his infamous stepfather, Alois Hitler changed his surname from Schicklgruber. Although raised by Johann Georg Hiedler, his biological father remains uncertain. Following Hiedler's demise, Alois' mother remarried Johann Georg Hitler. Alois pursued legal measures to adopt his stepfather's surname in 1876, cementing the infamous "Hitler" name associated with Adolf Hitler, the notorious Nazi leader and the atrocities of World War II.