Ar ôl dianc o'r Almaen cyn y rhyfel, bu farw mam y Dr Stern yn fuan ar ôl rhoi geni i'w chwaer fach, Erica. Bu farw ei dad, a oedd yn Iddew, yng ngwersyll crynhoi Buchenwald, ar ôl treulio amser yn Auschwitz.
Having escaped Germany before the war, Dr Stern’s mother died shortly after giving birth to his younger sister, Erica. His Jewish father died in Buchenwald concentration camp, after spending time in Auschwitz.