Talk about inbreeding, the leaders of three of the major countries in World War I were cousins: King George V of Britain, Czar Nicolas II of Russia, and Kaiser Wilhelm II of Germany were all decendants of Queen Victoria. Talk about family squabbles!!!
Nicholas II was not descended from Queen Victoria, although his wife was. Nicholas and George's mothers were daughters of the King of Denmark.
It's still a tangled web of cousin-breeding.