Shame on you! You seem unaware that the basic thesis of the book is ignored, but the IQ segments are blown out of proportion.
That book finds that economic status and family stability are the controlling factors. Which is universally ignored by the race baiters and their enablers.
No, the book finds that IQ correlates more strongly with success in life than socio-economic advantages. For example, white kids raised in poverty and dysfunction still have higher average IQs than black kids born and raised in comfort and stability. Similarly, twin studies discussed in the book show that twins raised apart have IQs more similar to each other than non-related children with which they're raised in the same household. The book is about the primacy of IQ, a largely heritable trait.
I take the whole book into consideration.
I also get my inforamation from anecdotal experience. 35 years in IT at 17 companies, as well as other endeavors.