Link, please. From a reliable source based on factual evidence that can be explained in no other way.
This issue has been regularly studied in great detail in medical journals and research. No explanation of the obvious should be required.
Here are some medical starting points. Complete with links to in-depth papers by leading researchers. I will let scientists argue if the differences are due to genes, environment, or other factors. The bottom line is that there are clear IQ test result differences across races. I am not going to make any assertions as to why.
The concept of using minimum IQ to disenfranchise citizens from voting is absurd and obviously would have an uneven effect across races. Likewise the “alt-right” clowns who like to use these IQ test results to lend justification to their ethno-nationalist politics are also absurd.
Race differences in average IQ are largely genetic
A 60-page review of the scientific evidence, some based on state-of-the-art magnetic resonance imaging (MRI) of brain size, has concluded that race differences in average IQ are largely genetic.
https://www.news-medical.net/news/2005/04/26/Race-differences-in-average-IQ-are-largely-genetic.aspx
The lead article in the June 2005 issue of
Psychology, Public Policy and Law, a journal of the
American Psychological Association, examined 10 categories of research evidence from around the world to contrast "a hereditarian model (50% genetic-50% cultural) and a culture-only model (0% genetic-100% cultural)."
The paper, "Thirty Years of Research on Race Differences in Cognitive Ability," by J. Philippe Rushton of the
University of Western Ontario and Arthur R. Jensen of the
University of California at Berkeley, appeared with a positive commentary by Linda Gottfredson of the
University of Delaware, three critical ones (by Robert Sternberg of
Yale University, Richard Nisbett of the
University of Michigan, and Lisa Suzuki & Joshua Aronson of
New York University), and the authors' reply.
"Neither the existence nor the size of race differences in IQ are a matter of dispute, only their cause," write the authors. The Black-White difference has been found consistently from the time of the massive World War I Army testing of 90 years ago to a massive study of over 6 million corporate, military, and higher-education test-takers in 2001.
"Race differences show up by 3 years of age, even after matching on maternal education and other variables," said Rushton. "Therefore they cannot be due to poor education since this has not yet begun to exert an effect. That's why Jensen and I looked at the genetic hypothesis in detail. We examined 10 categories of evidence."
- The Worldwide Pattern of IQ Scores. East Asians average higher on IQ tests than Whites, both in the U. S. and in Asia, even though IQ tests were developed for use in the Euro-American culture. Around the world, the average IQ for East Asians centers around 106; for Whites, about 100; and for Blacks about 85 in the U.S. and 70 in sub-Saharan Africa.
- Race Differences are Most Pronounced on Tests that Best Measure the General Intelligence Factor (g). Black-White differences, for example, are larger on the Backward Digit Span test than on the less g loaded Forward Digit Span test.
- The Gene-Environment Architecture of IQ is the Same in all Races, and Race Differences are Most Pronounced on More Heritable Abilities. Studies of Black, White, and East Asian twins, for example, show the heritability of IQ is 50% or higher in all races.
- Brain Size Differences. Studies using magnetic resonance imaging (MRI) find a correlation of brain size with IQ of about 0.40. Larger brains contain more neurons and synapses and process information faster. Race differences in brain size are present at birth. By adulthood, East Asians average 1 cubic inch more cranial capacity than Whites who average 5 cubic inches more than Blacks.
- Trans-Racial Adoption Studies. Race differences in IQ remain following adoption by White middle class parents. East Asians grow to average higher IQs than Whites while Blacks score lower. The Minnesota Trans-Racial Adoption Study followed children to age 17 and found race differences were even greater than at age 7: White children, 106; Mixed-Race children, 99; and Black children, 89.
- Racial Admixture Studies. Black children with lighter skin, for example, average higher IQ scores. In South Africa, the IQ of the mixed-race "Colored" population averages 85, intermediate to the African 70 and White 100.
- IQ Scores of Blacks and Whites Regress toward the Averages of Their Race. Parents pass on only some exceptional genes to offspring so parents with very high IQs tend to have more average children. Black and White children with parents of IQ 115 move to different averages--Blacks toward 85 and Whites to 100.
- Race Differences in Other "Life-History" Traits. East Asians and Blacks consistently fall at two ends of a continuum with Whites intermediate on 60 measures of maturation, personality, reproduction, and social organization. For example, Black children sit, crawl, walk, and put on their clothes earlier than Whites or East Asians.
- Race Differences and the Out-of-Africa theory of Human Origins. East Asian-White-Black differences fit the theory that modern humans arose in Africa about 100,000 years ago and expanded northward. During prolonged winters there was evolutionary selection for higher IQ created by problems of raising children, gathering and storing food, gaining shelter, and making clothes.
- Do Culture-Only Theories Explain the Data? Culture-only theories do not explain the highly consistent pattern of race differences in IQ, especially the East Asian data. No interventions such as ending segregation, introducing school busing, or "Head Start" programs have reduced the gaps as culture-only theory would predict.
(more at above url)
The book extract article below take the perspective that differences are due to environment and not genetics.
The Black-White Test Score Gap
https://archive.nytimes.com/www.nytimes.com/books/first/j/jencks-gap.html?mcubz=3