- Linda Gottfredson, who was awarded the Mensa Award for Excellence in Research in 2005, the Faculty Senate Commendation for Extraordinary Leadership and Service by the university of Delaware in the same year, the Mensa Research Foundation Award for Excellence in Research (1999 – 2000) and many others, wrote in an article entitled The General Intelligence Factor
“Studies comparing identical and fraternal twins, published in the past decade
by a group led by Thomas J. Bouchard, Jr. of the University of Minnesota and other scholars, show that about 40 percent of IQ differences among preschoolers stems from genetic differences but that heritability rises to
60 percent by adolescence and to 80 percent by late adulthood”.
- Harvard professor Richard Herrnstein and political scientist Charles Murray conclude in their best-selling, and co-authored book The Bell Curve that intelligence is about 40 – 80% genetically determined. 
- Professor of educational psychology, Arthur Jensen, states in his book The g Factor that intelligence is 80% determined by genetics and 20% by environment. 
- Professors Richard Lynn and Tatu Vanhanen come to the conclusion in their book The Wealth of Nations that the average IQ for East Asians is 105, 100 for Europeans, 91 for the Inuit, 87 for South East Asians and Native Americans, 85 for Pacific Islanders, 84 for South Asians and North Africans, 67 for sub-Saharan Africans, 62 for Australian Aboriginals, and 54 for Pygmies of the Congo rain forests.