Passage: Despite his British citizenship, his marriage and five British sons, de László was interned for over twelve months in 1917 and 1918 during the First World War. He was exonerated and released in June 1919. Due to overwork de László suffered heart problems for the last years of his life. In October 1937 he had a heart attack and died a month later at his home, Hyme House, in Hampstead, London.In 1939, Portrait of a Painter. The Authorized Life of Philip de László by Owen Rutter, written in conjunction with de László, was published. In 2010 Yale University Press published De László, His Life and Art by Duff Hart-Davis and Dr. Caroline Corbeau-Parsons. His reputation still remains largely as a society portrait painter, but well numbered amongst his sitters were industrialists and scientists, politicians and painters, men and women of letters and many other eminent, as well as ordinary, people. Family members and a team of editors are compiling a catalogue raisonné published online and in progress. His oeuvre currently numbers almost 4,000 works, including drawings.

Question: What is the nationality of de Laszlo's sons?
British