2. Yes.

Doesn't change the fact that most comportments and interests are mainly ruled by social environment and upbringing, and biology only have this little impact (and it is still probably less that my brain will attribute, but at least i'm self-aware: https://en.wikipedia.org/wiki/Fundamental_attribution_error).

Unless you think poor people are biologically less interested in space, earth crust, plants, sailing, horseriding, i'd be pretty confident in saying that most differences between children are in fact solely based on culture. This might evolve later (puberty hit!), but considering childhood is the crux of so much of your later choices

I've been a youth camp counselor, and in my country, classes are not always segregated when going to those camps (they are more and more tbh), and with this experience i can say: you tell me your child hobbies and dreams, i can tell you your income quintile (or social class rather, as cultural inheritance is not always correlated to income), whether it's a boy or girl, and if his family emigrated recently. Only work if you're from my country, but i'm sure if you talk to any youth camp counselor in your country who cared and worked this job for six+ years, he'd be able to do the same.