Lol, yes it's acommon joke in the UK that the Royal Family are German, but that's not the whole truth. You could also say that since every current member of every European Royal family is decended from Queen Victoria (and all the way back to George I), they are all also English. The fact that the King of England and the German Emperor during World War One were first cousins didn't help, and that's the reason why the British Royals tried to distance themselves from their German cousins by becoming the House of Windsor. Basically the practice of Royals only marrying other Royals for centuries led to them all being the same extended family.