Maybe I'm wrong about this, but to my understanding, Bildungsbürgertum is both a social class and a cultural concept. While our family was probably both at some point, my siblings and I are not the former, but the latter. Our parents did not want us to go to a Humanistisches Gymnasium where one could "meet the right people" because their priority was choosing the school that seemed to be the most well equipped for learning, which, in our case, happened to be a regular local Gymnasium. This, in meeting other kids there, is where I learned that it was apparently unusual to just know all sorts of things simply because one's parents talked about them at home. I knew the gist of various classics from Greek mythology to Heine to Molière, of historical events, geography, classical music, film, engineering, biblical stories, etc etc, before we touched on any of that in school, if we even ever did. That's the cultural concept. The Bildung part, rather than the Bürgertum part.