[zo1]

Twin vs sibling studies aim at quantifying what effect genetics has on IQ rather than environmental conditions. If there are hereditary components to it, then they most certainly can be mapped to some extent across population groups, as have a lot of other "traits". There are only so many ways to slice this, but it is unfortunately a delicate topic.

[diffrinse]

Question, are the studies telling us IQ is heritable or telling us a dumb person can't have smart kids?