
The book was controversial, especially where the authors wrote about racial differences in intelligence and discussed the implications of those differences. The authors were reported throughout the popular press as arguing that these IQ differences are genetic. They wrote in chapter 13: "It seems highly likely to us that both genes and the environment have something to do with racial differences." The introduction to the chapter more cautiously states, "The debate about whether and how much genes and environment have to do with ethnic differences remains unresolved."
The book's title comes from the bell-shaped normal distribution of intelligence quotient (IQ) scores in a population.
Shortly after publication, many people rallied both in criticism and defense of the book. A number of critical texts were written in response to the book."(Wikipedia)
*Because this book can be seen as racist and promoting racism, I will not provide links.