Your middle link there refers to the Minnesota Transracial Adoption Study [1]. That brief seems to assume the reader is familiar with the studies as otherwise i

Your middle link there refers to the Minnesota Transracial Adoption Study [1]. That brief seems to assume the reader is familiar with the studies as otherwise it would be very easy to misunderstand what they're saying - which is not what you're saying. Their study was a large undertaking studying the differences in black/interracial/white children who were all adopted by wealthy white families in Minnesota. It found that at age 7 the difference in IQ between a adopted white child and adopted black child was 20.1 points. At age 17 this changed to 17.8 points. The difference for a half black child and a white child was 6.1 at age 7, and 8.3 at age 17. The goal of the study was to show the opposite of what it ended up showing. Consequently many individuals, including the authors of the study themselves, have tried to argue that this is not evidence of a genetic link to IQ. Arguments against it have run the gamut from environmental factors from before the children were adopted (which was at less than 1 years old in all cases) to skin color causing environmental effects. These are certainly contributing factors, however they would undermine any and all results of the study - which is indicative of an after-the-fact effort to undermine their own results. In either case, that result certainly showed nothing like "family environment mattered a hell of alot." The misunderstanding here probably comes from one questionably phrased sentence in that abstract, "Black and interracial children scored as well on IQ tests as adoptees in other studies." That is more clearly read as "Black and interracial children scored as well on IQ tests as black and interracial adoptees in other studies." In other words, they're comparing differences between 'same group' individuals and trying to see what determines the variance there. And they found that at a young age this is frequently related to environmental factors, whereas at older age genetics becomes dominant even among 'same 'group individuals. In the abstract's rather kinder phrasing, "Our interpretation of these results is that younger children are more influenced by differences among their family environments than older adolescents, who are freer to seek their own niches.".