JRR Tolkien offers a stiff reply to a German publisher asking after his Aryan origins. He sent it via his publisher, along with a more co-operative letter, so giving his publisher the option to send either one. It is unknown which reply was sent.
Tolkein surely wasn't the only one. A request like that would have been sent to a lot of bestselling British authors in the 1930s; Germany remained a viable market. I wonder if any record exists of how they replied.