Klaus Fuchs' family was not of Jewish descent as stated by General Walter Bedell Smith. He was the son of the Lutheran vicar, eminent theologian, and member of the social democratic party in Germany (SPD), Emil Fuchs. Klaus Fuchs left Germany August 1933 to escape political persecution by the Nazis because of his communist convictions.
Klaus Fuchs claims, in this episode, that his wife had committed suicide before the start of the war as a political protest against the Nazis. In point of fact, Fuchs did not marry until 1959. His mother committed suicide, but in 1930, before the Nazis came to power.
Klaus Fuchs [from his confession to having been a Soviet spy, January 27, 1950] "At first I thought that all I would do would be to inform the Russian authorities that work upon the atomic bomb was going on. They wished to have more details and I agreed to supply them. I concentrated at first mainly on the product of my own work, but in particular at Los Alamos I did what I consider to be the worst I have done, namely to give information about the principle of the design of the plutonium bomb . . . The last time when I handed over information was in February or March 1949."