Gustav IV Adolf of Sweden
Karl was born at Straßburg, German Empire (which later became Strasbourg in France) (some websites have erroneously give Straßburg, Austria), the second child and first son of Emich, 5th Prince of Leiningen (1866–1939) (son of Ernst Leopold, 4th Prince of Leiningen and Princess Marie Amelie of Baden) and his wife, Princess Feodore of Hohenlohe-Langenburg (1866–1932) (daughter of Hermann, Prince of Hohenlohe-Langenburg and Princess Leopoldine of Baden). Through his father he was descendant of Gustav IV Adolf of Sweden.