In the case of the foster children, they initially scored low on IQ test but once placed in a better environment their scores went up significantly. This demonstrates that environment can have a huge effect on IQ scores and casts doubt on tests which claim that a correlation between IQ and family members implies IQ is mostly a result of genetics. Since family members generally live in similar environments their similar IQ scores can be explained by environment. It is even plausible that IQ score is mostly a result of environment.

Now, I can not prove that to be the case but it is far from settled that better genes = better IQ = better socioeconomic status. That reasoning implies that people in third world countries are poor because they are stupid which I just don't believe, partly because I've actually been to some of those countries.