Happy Birthday to the Princess of Prussia, who turns 40 today! The daughter of the Prince of Isenburg and Countess Christine von Saurma-Jeltsch, she is the sister of Hereditary Prince Alexander, Archduchess Katharina of Austria-Este, and the Dowager Princess of Wied, and Prince Viktor. Growing up at Birstein Castle, she studied in Germany at the University of Freiburg and Humboldt University of Berlin and works at a firm that offers consulting services for nonprofit business. In 2011, Princess Sophie married Georg Friedrich, the Prince of Prussia, the Head of the House of Hohenzollern and the pretender to the former German Empire. The couple have four children, and reside at Burg Hohenzollern, where despite having no official duties, the Prince and Princess wield cultural and charitable influence.