Question: The great-great-grandfather of current head of the House of Hohenzollern held what official title?
Sentence (from "Countess Donata of Castell-Rüdenhausen"): She was the mother of Prince Georg Friedrich of Prussia (born 1976) the current head of the House of Hohenzollern, the ruling dynasty of the German Empire and of the Kingdom of Prussia until 1918.
Relevant evidence: No