Sophie was born on 7 March 1978 in Frankfurt, West Germany.[2] Her parents are Franz-Alexander, Prince of Isenburg and his wife, née Countess Christine von Saurma-Jeltsch.[3] He is head of a mediatized Catholic line of Princes of the Holy Roman Empire, who lost their independence in 1815.[3] She has two sisters (Archduchess Katharina of Austria-Este and Isabelle, Dowager Princess of Wied) and two brothers (Hereditary Prince Alexander and Prince Viktor).[3][4]