O laf Köndgen is 64 years old, a German citizen and a senior European human rights expert who has lived and worked in France for several years. Last month, Köndgen learned that he is also the son of a Nazi. Despite a strong interest in history and its lessons, Köndgen is typical of many 21st-century Germans in having had only the roughest outlines of his own family’s complicity with Hitler’s regime. Olaf Köndgen’s father, Ernst, on home leave from the eastern front in 1942. Photograph: Supplied That began to change in early April, when the newspaper Die Zeit launched an online search engine for the vast archives of the National Socialist German Workers’ party (NSDAP), making information about individuals’ Nazi membership easily accessible for the first time. Die Zeit has described an extraordinary response from the public, reflecting intense interest in unearthing long-buried family secrets more than eight decades after the end of the second world war.…