Prince Hermann is the elder son of the late Prince Karl of Leiningen and Princess Marie Louise of Bulgaria, whose brother, Simeon, is the former king.
Prince Hermann is a descendant of Queen Victoria through his father, Prince Karl, whose mother was Grand Duchess Maria Kirillovna of Russia, the eldest of three children of Grand Duke Kirill of Russia and Princess Victoria Melita of Edinburgh, second daughter of Prince Alfred, Duke of Edinburgh, Duke of Edinburgh, Duke of Saxe-Coburg and Gotha and Grand Duchess Marie Alexandrovna of Russia, whose brother, Grand Duke Wladimir, whose son was Grand Duke Kirill who married his first cousin.
Princess Marie Louise is the elder of two children of King Boris III of the Bulgarians and Princess Giovanna of Savoy, daughter of King Victor Emmanuel of Italy and his wife, Princess Elena of Montenegro.
The present Prince of Leiningen - Andreas - is Hermann's first cousin. Prince Hermann remains a dynast, as does his brother, Boris, although neither are likely to ever succeed. The Leiningen house law does not require "equal marriage." Prince Karl Emich lost his position because his father did not approve of his marriage to a particular commoner, Gabriele Thyssen. Karl-Emich went against his father's wishes, married Gabriele, an action that infuriated his father, who called his lawyer, and changed his will. This was complicated by the establishment in 1925 of a family trust in order to protect the family estate. Karl-Emich, when he turned 35, had already inherited a percentage of the estate.
Although Karl-Emich's marriage to Gabriele Thyssen ended in divorce, and she moved on to a much bigger fish, he did not regain his rights. Although he is now married to a countess and is the father of a new-born son, Karl Emich (and his male line) are not dynasts.
Karl-Emich and his second wife were styled as the Prince and Princess of Leiningen after Emich's death. This was due to the legal maneuverings, as the case wended its way through the German courts. In the end, Karl-Emich accepted the decision, and ceased to be styled as the Prince of Leiningen, as if he had never succeeded his father. He accepted (as have other members of the princely family) that his younger brother, Andreas, succeeded their father, and is the Prince of Leiningen. The Leiningen house laws are specific in various matters, including the succession, but an equal marriage requirement is not included. The German courts ruled not on the succession issue, but on the requirements set out in the late Prince of Leiningen's will. A precedent had already been established with the court ruling regarding the will of the late Kaiser Wilhelm II, and how his will defined the succession and inheritance in Prussia.
The late Gustav, Prince of Sayn-Wittgenstein-Berleburg's final will included clauses regarding inheritance, and, it is because of this will, his grandson, Prince Gustav, cannot marry his longtime love, Carina Axelsson, without losing his inheritance.
[Little fincky Finns should never meddle with a pro!]