Jewish folks seem to be suceptible to the left wing virus, that’s for sure. The success of the left in painting Hitler as an antileftist has probably contributed to the epidemic, post World War II. Others have commented on this proclivity far more knowledgably and articulately than I ever could. American WASPs seem to succumb to the disease in even greater numbers, (e.g., Alger Hiss, Harry Dexter White, Elizabeth Bentley...) although, presumably at a lower rate. The infection rate among Anglo-Saxons in Oxbridge during the 1930’s was close to 100%, rivaling the contemporaneous outbreak among Jews at CCNY.
The Cold War was actually started in the 1920s. The Russians viewed the freedom and economic success of the United States as a refutation of Marxist theory. As long as the United States suceeded, critics of Marxism had at least one counter example to point to. Hostility of the Soviets to the United States was not predicated on existence or actions of any single ethnic group. Many individual Jews in the West aligned themselves with the Soviet Union for more or less the same reasons that Western eggheads did.
I am not sure of the exact number but I believe less than a dozen were ever prosecuted. The real outrage of the McCarthy era was not innocent people accused of being Communists, it was guilty Communist agents going unpunished.
Side Note: It would be interesting to have a list of current high profile “progressives” whose parents were on the payroll of the Soviet Union.
AL Gore family received large sums of money from Soviet Agent Armand Hammer, John Kerry's father was part of a pro-soviet clique in the 1950s State Department and later on Mr. Kerry became a virtual North Vietnamese Agent, Obama had Communist Mentors as did Hillary.