Real talk: which kids have you interacted with? What social class? What ethnicity? What household structure (nuclear, multigenerational, single parent, single parent plus intermittent partner, divorced with shared custody, dirtbag but grandparent covering)?
I've found that the people who are more optimistic about kids tend to live in a particular category of socioneconomic bubble.
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.