Agreed, "culture" is a symptom, not a cause.

All humans are the same species, and in a vacuum, have no ideas or inherent behaviors beyond base instinct.

Culture is simply a byproduct of the environment around a segment of humans.

Hence, filtering by white kids in the US simply measures the result of higher average economic status (same as filtering by Asian kids).

American outcomes would look better if the populations they economically disenfranchised historically stayed in other countries like Europeans did with the colonial system (vs importing populations as slave labor domestically in the US). The economic class stratification that still lingers as a result of this in the US is such a unique factor as to make comparisons that don't take this into account worthless.