I wouldn’t say he is German, but German dynasties have sit on the British throne since George I was crowned in 1714. Up till queen Victoria all monarchs belonged to the house of Hanover. Victoria married Albert of house Saxe-Coburg and Gotha, and their son Edward VII was counted as the member of that dynasty. Edward’s son George V changed their surname to “Windsor” in 1917.
And i imagine that the house of Saxony which part house Saxe-Coburg and Gotha is, is pretty inbred since basically every surviving european noble today is either part of it or closely related.