One hundred years ago, the popular banishment of foreign control over British affairs very nearly overthrew the monarchy. No wonder that the Queen is so anxious to quash any suggestion that she would wish to set off that kind of thing again.
Her father was a product of many generations of immigrant cousin marriage, and she herself has one. Think of her as a Bradford Pakistani, or as a Tower Hamlets Bangladeshi. Except that those are of Commonwealth origin.
Numerous of the Queen's and her husband's relatives fought for Germany in the two World Wars, including a cousin of both, Queen Victoria's youngest grandchild, who was born in Surrey, fought for his cousin (and theirs) the Kaiser, became Hitler's Ambassador to London, and ended up a convicted Nazi war criminal.
All very Jihadi John.