Yeah, these are less puzzling when you realize that nazi defined Jewishness by blood and thus many assimilated people who considered themselves Germans and believed same things as other Germans got catch in net too.
Which was oddly less strict than in the American South where one drop of Black blood was enough to make you not White. As far as determining blood mixing in the Reich the Mischling Test was used and if you had 3 grandparents who were Jewish that made you Jewish.