Ronald C. Johnson argued that if early environmental stimulation or deprivation has a significant effect on intellectual ability, then individuals who are genetically identical and who are exposed to a common early environment should resemble one another more closely in IQ than similar individuals who have not shared a common environment. Johnson…

Extensive data on twins, nontwin siblings, siblings separated by adoption, and parent-child similarity indicate that the heritability of intelligence is closer to .50 than to .70. Differences could be due to environmental or genetic changes in the population, or to methodology. (Author/CP)

Wolff has recently reinterpreted the data of Lee to indicate that Black migration from the south to Philadelphia had been selective in an IQ-relevant manner. However, Wolff's deduction from Lee's data is shown to depend entirely upon an assumption about cumulative IQ deficit in southern Black children. (Author/CTM)

Kamin has contended that arguments presented in Wolff are too weak to justify selective migration. Although Kamin's critique points up the need for closer scrutiny of the cumulative-deficit phenomenon, it fails to refute Wolff's conclusion that selective migration is partly responsible for the North-South Black IQ differential. (Author/CTM)

This book is organized in nine parts, as follows. Part I, "Preface," includes an account of how the author went from the rather esoteric research on theoretical problems in serial rote learning to research on the inheritance of mental abilities and its implications for education. Part II, "How Much Can We Boost IQ and Scholastic Achievement?," is…

This paper deals with the issue of black-white differences in cognitive skills. Some authorities attribute these differences to differences in the environments of black and white homes. Others state that the differences are due to differences in genes, i.e., heredity. Scholars holding these two opposing views have become more or less entangled in…