There have been twin adoption studies where one black twin was adopted by an upper middle class white family while the other black twin was adopted by a less affluent black family. There is no statistical difference in IQ scores between between the black twin raised in more affluent , intellectually stimulation environment, and the other twin raised in a less affluent ,intellectually stimulating environment.
The g factor by Arthur R. Jensen, deals with the nonsensical arguments that black/white IQ differences are environment-related. While he concludes that 80% of IQ is purely related to inheritance (genetics), the remaining 20% cannot be explained by the usual excuses for black-white differences. In his chapter on population differences in g (which represents the trait measured by IQ testing), Jensen estimates actual numerical ratio of white/black IQ above 130 in the US is about 150 to one. This is why all mail addressed to Jensen must first go through special explosive detection and poison detection machines at his local post office before it is delivered to him. This incredible hostility toward Jensen began in 1969 when he was invited to write an article for the Harvard Educational Review about the degree ,if any ,could white/black IQ differences be narrowed. He had the courage to conclude all of the programs designed to narrow white/black scholastic differences were doomed to failure. No one in academia can find any significant faults in any of Jensen's publications, because Jensen is a pure scholar without any agenda.
