Ignoring whatever you mean by injecting "ethnicity" into the question, I've interacted kids in all of those socio-economic situations and think both that GP's point about innate curiosity is true, and that GGP's unwilling / coaxable / eager concept is a reasonable framework. That's not to say that I'm necessarily optimistic - socio-economic difficulties create absolutely enormous challenges to learning - just that I've never encountered a group of kids, regardless of background, where there weren't students in each of those (unwilling / coaxable / eager) sets.