Malcolm Gladwell and the birth of a "fact"

Are biracial children with White mothers smarter than those with Black mothers?

Malcolm Gladwell, author and staff writer at The New Yorker

When I first published my last post in Aporia Magazine, a reader told me that Black mother/White father children not only have worse birth outcomes than White mother/Black father children but also are eight points lower in IQ.

The source for this fact? Malcolm Gladwell, a staff writer at The New Yorker and a popular author. Eight years ago, in an article for this magazine, he argued that genetics cannot explain IQ differences between human populations, particularly the gap between Euro and African Americans. He recalled two points that Flynn had made in a debate on this subject with Charles Murray.

First, the IQ gap differs by age:

Flynn took a different approach. The black-white gap, he pointed out, differs dramatically by age. He noted that the tests we have for measuring the cognitive functioning of infants, though admittedly crude, show the races to be almost the same. By age four, the average black I.Q. is 95.4—only four and a half points behind the average white I.Q. Then the real gap emerges: from age four through twenty-four, blacks lose six-tenths of a point a year, until their scores settle at 83.4. (Gladwell, 2007)

Second, the IQ gap is affected by a strange interaction between race and gender:

Flynn then talked about what we’ve learned from studies of adoption and mixed-race children—and that evidence didn’t fit a genetic model, either. If I.Q. is innate, it shouldn’t make a difference whether it’s a mixed-race child’s mother or father who is black. But it does: children with a white mother and a black father have an eight-point I.Q. advantage over those with a black mother and a white father. (Gladwell, 2007)

Here, Flynn was following the argument he had made in an American Psychologist article on the same subject (Flynn, 1999). But that article has no comparison between Black mother/White father children and White mother/Black father children. Nor does any other article of his.

Gladwell probably heard something like the following, in which Flynn summarized Klaus Eyferth’s study of illegitimate children born to German mothers and fathered by American soldiers:

The soldiers of the American occupation force in Germany, both White and Black, fathered thousands of children with German women after World War II. Eyferth (see Flynn, 1980) selected a representative sample of 181 Black children and a matching group of 83 White children and found that their mean IQs were virtually identical. In other words, children who had a White father seemed to possess no advantage whatsoever over those who had a Black father. (Flynn, 1999, p. 14)

Evidently, the mothers were White in both groups.

A reader has brought to my attention another study, not mentioned by Flynn in his American Psychologist article, that corresponds more closely to what Gladwell remembered. Willerman et al. (1974) administered a cognitive test at 4 years of age to 101 biracial children who had White mothers with 28 who had Black mothers. The first group averaged about 9 IQ points higher than the second.

Was Gladwell inserting this finding into his memory of Flynn’s presentation? It’s a dubious finding at best.

• First, the black mother sample is small. The rule of thumb is to have a minimum of 30 to 40 individuals for statistical comparison (Varshney, 2023).

• Second, educational level was higher for both parents when the mother was white than when she was black. This, in itself, is a red flag, since the situation is usually the reverse (see my previous post). The authors tried to control for this difference by controlling for maternal education but not for both maternal and paternal education. If you’re trying to rule out a genetic explanation—and this was the intent of the study—you should control for the education of both parents, since educational attainment correlates highly with the genetic component of cognitive ability, and since both parents would presumably be passing on this genetic component. This adjustment was not done because “because educational data on 25% of the fathers were lacking.”

• As will be shown further in this post, IQ is much more malleable at younger ages than at older ages. IQ before adulthood, and even more so during early childhood, is more strongly influenced by the family environment.

But other than that …

Does Malcolm Gladwell nonetheless have a point with respect to the Eyferth study? If genetic factors are so important, why did the biracial children in that study have the same mean IQ as the White children?

Three reasons were given by Rushton and Jensen (2005, p. 261):

• The US Army screened out low-IQ enlistees through the Army General Classification Test, essentially an IQ test. The rejection rate was about 30% for African Americans and 3% for Euro Americans. The African American soldiers in Germany were thus a higher-IQ sample of the African American population.

• Between 20 and 25% of the “black” fathers were, in fact, North African, i.e., Moroccan and Algerians soldiers serving in the French army of occupation.

• The children were still young when tested. One third were between 5 and 10 years old and two thirds between 10 and 13. Since IQ is strongly influenced by family environment before puberty, a much larger sample would have been needed to show a significant difference between the two groups.

The last point leads us to a related one: the capacity for learning seems to be greater in children than in adults. This might explain one aspect of the Minnesota Transracial Adoption Study (Weinberg et al., 1992; see also Levin, 1994; Lynn, 1994). In the enriched learning environment of middle-class Minnesota families, all of the children showed impressive IQ scores by 7 years of age. By 17 years of age, however, this IQ boost had largely faded out:

Mean IQs of participants in the Minnesota Transracial Adoption Study, by race and by age

Discussion has focused on the finding that the relative positions of the four groups remained unchanged between age 7 and age 17. Mean IQ declined, however, in all four groups. Weinberg et al. (1992) attributed the decline to a renorming of the IQ test from the WAIS to the WAIS-R, noting that this change had typically caused declines of the same order in other studies. On the other hand, the Flynn effect should have caused a 3-point increase over the intervening 10 years. Also, the WAIS was only one of three IQ tests used in the study:

In interpreting this decline, one must keep in mind that different IQ tests were employed at Time 1 and Time 2. Depending on their ages, family members were tested using the Stanford-Binet Form L-M (Terman & Merrill, 1973), WISC, or WAIS in the original study, and using the WISC-R or WAIS-R in the follow-up study. (Weinberg et al.,1992, p. 130)

The authors contented themselves with the conclusion that “most of this decline” could be explained by the WAIS renorming.

We know that the capacity to learn and retain information declines with age, as noted by IQ researcher David Weschler:

Beginning with the investigation by Galton in 1883 and continuing up to and including the most recent studies of Pacaud, nearly all studies dealing with the age factor in adult performance have shown that most human abilities, in so far as they are measurable, decline progressively, after reaching a peak somewhere between ages 18 and 25 (Weschler, 1958).

But the peak came earlier in the Minnesota study. Perhaps the peak between 18 and 25 is preceded by a gradual lowering of the ceiling for learning saturation. This ceiling may be more often reached by children in the enriched learning environment of adoptive middle-class families. A similar decline has been noticed with Head Start in the U.S. — a preschool educational program that has typically shown impressive IQ gains that fade out as the children get older (Barnett et al., 2005).

The same is true for offspring in nonhuman species. An animal is more receptive to learning during infancy, when it is exploring its world. Its capacity for learning then declines as it gets older. In dogs, age-related cognitive decline seems to be independent of variation in physiological aging and lifespan among different breeds (Watowich et al., 2020). Dogs lose their ability to learn because it is less advantageous for them to learn as they transition from infancy to adulthood.

In our species, the decline is weaker and pushed forward in time because it is more advantageous for us to keep learning.

References

Barnett, W. S., & Hustedt, J. T. (2005). Head Start's lasting benefits. Infants & Young Children, 18(1), 16-24. https://psycnet.apa.org/doi/10.1097/00001163-200501000-00003

Caplan, B. (2007). Gladwell on IQ: My Chance to Answer Two Plausible But Over-rated Arguments, EconLog, December 14. https://www.econlib.org/archives/2007/12/gladwell_on_iq.html

Eyferth, K. (1961). Leistungen verscheidener Gruppen von Besatzungskindern in Hamburg-Wechsler Intelligenztest für Kinder (HAWIK). Archiv für die gesamte Psychologie, 113, 222-241.

Flynn, J. R. (1999). Searching for justice: the discovery of IQ gains over time. American Psychologist, 54(1), 5. https://psycnet.apa.org/doi/10.1037/0003-066X.54.1.5

Frost, P. (2019). IQ of biracial children and adults, Evo and Proud, March 10. https://evoandproud.blogspot.com/2019/03/iq-of-biracial-children-and-adults.html

Gladwell, M. (2007). None of the Above. The New Yorker. https://www.newyorker.com/magazine/2007/12/17/none-of-the-above

Levin, M. (1994). Comment on the Minnesota transracial adoption study. Intelligence, 19(1), 13-20. https://doi.org/10.1016/0160-2896(94)90049-3

Lynn, R. (1994). Some reinterpretations of the Minnesota transracial adoption study. Intelligence, 19(1), 21-27. https://doi.org/10.1016/0160-2896(94)90050-7

Rushton, P. & Jensen, A.R. (2005). Thirty years of research on race differences in cognitive ability. Psychology, Public Policy, and Law, 11, 235-294. https://psycnet.apa.org/doi/10.1037/1076-8971.11.2.235 https://isgp-studies.com/miscellaneous/race-and-iq/2005-APA-Rushton-Jensen-Thirty-Years-of-Research-on-Race-Differences-in-Cognitive-Ability.pdf

Varshney, D. (2023). Re: What is the minimum sample size for t-test?. Retrieved from: https://www.researchgate.net/post/What_is_the_minimum_sample_size_for_t-test/6468fa914e2ff22fde0e5fd8/citation/download.

Watowich, M. M., MacLean, E. L., Hare, B., Call, J., Kaminski, J., Miklósi, Á., & Snyder-Mackler, N. (2020). Age influences domestic dog cognitive performance independent of average breed lifespan. Animal Cognition, 23, 795-805. https://doi.org/10.1007/s10071-020-01385-0

Wechsler, D. (1958). Changes in Intelligence and Intellectual Ability with Age. In D. Wechsler, The measurement and appraisal of adult intelligence (4th ed., pp. 135–143). Williams & Wilkins Co. https://doi.org/10.1037/11167-009

Weinberg, R. A., Scarr, S., & Waldman, I. D. (1992). The Minnesota Transracial Adoption Study: A follow-up of IQ test performance at adolescence. Intelligence, 16(1), 117-135. https://doi.org/10.1016/0160-2896(92)90028-P

Wikipedia. (2025). Malcolm Gladwell. https://en.wikipedia.org/wiki/Malcolm_Gladwell

Willerman, L., Naylor, A. F., & Myrianthopoulos, N. C. (1974). Intellectual development of children from interracial matings: Performance in infancy and at 4 years. Behavior Genetics, 4(1), 83-90. https://doi.org/10.1007/BF01066706