This is from a letter Tolkien wrote to the German publishers Rutten & Loening Verlag in 1938. Before translating and publishing "The Hobbit" in German, they had written to ask if he was of Aryan origin.
25 July 1938
20 Northmoor Road, Oxford
Thank you for your letter... I regret that I am not clear as to what you intend by aryan. I am not of Aryan extraction: that is Indo-iranian; as far as I am aware none of my ancestors spoke Hindustani, Persian, Gypsy, or any related dialects. But if I am to understand that your are enquiring whether I am of Jewish origin, I can only reply that I regret that I appear to have no ancestors of that gifted people. My great-great-grandfather came to England in the eighteenth century from Germany: the main part of my descent is therefore purely English, and I am an English subject -- which should be sufficient. I have been accustomed, nonetheless, to regard my German name with pride, and continue to do so throughout the period of the late regrettable war, in which I served in the English army. I cannot, however, forbear to comment that if impertinent and irrelevant inquiries of this sort are to become the rule in matters of literature, then the time is not far distant when a German name will no longer be a source of pride.
Your inquiry is doubtless made in order to comply with the laws of your own country, but that this should be held to apply to the subjects of another state would be improper, even if it had (and it had not) any bearing whatsoever on the merits of my work or its suitability for publication, of which you appear to have satisfied yourselves without reference to my origins (Abstammung).
I trust you will find this reply satisfactory, and
remain yours faithfully
Letters, 29 #37