In 2006, Dr. Lawrence Summers resigned as president of Harvard University partly due to a non-confidence vote by Harvard’s faculty, which resulted from Summers’ controversial remarks that women are under-represented at the top end of math, science, and engineering fields because women have “different availability of aptitude at the high end”. In his remarks he mostly dismissed the possibility that the under-representation of women in science fields was due to socialization differences or discrimination (visit Women in Science and Engineering Leadership Institute at the University of Wisconsin for an amazing collection of resources related to the Summers case).

Although many studies have been conducted on this issue, a study scheduled to be published on the Journal of Child Psychology and Psychiatry greatly informs this debate by disentangling, to a significant extent, the relative contributions of genetics and environment to the possible sex differences in math and science achievement.

In the article the authors examined 3,000 pairs of British twins when they were 9, 10, and 12 years of age. Specifically, the authors reviewed teachers’ reports of the kids’ academic performance and examined the genetic and environmental predictors of “high science ability”.

The results:

  1. Despite the unusually large sample size, there was no difference in standardized achievement scores between boy and girl twins at any of the 3 time points. The large sample size is worth noting because large sample sizes make the identification of significant differences much easier.
  2. Boys were more likely to be at the high end of performance at age 9, but this sex difference was not present at age 10 or 12.
  3. Finally, the authors examined a model that used Monozygotic male pairs (MZM), Dizygotic male pairs (DZM), Monozygotic female pairs (MZF), Dizygotic female pairs (DZF), and Dizygotic opposite sex pairs (DZOS) to determine the relative contributions of genetic and environmental differences to science achievement.   This model suggested that both genetic and environmental factors have a similar effect on science performance for both boys and girls.

This last finding is highly informative. The model indicated that there was no difference between boys and girls in how they are affected by genetic and environmental factors. Theoretically, if girls’ science achievement was due to limited aptitudes (related to some neurocognitive difference for example), they would be affected by environmental and genetic factors differently than boys (for example by being less responsive to the same environmental conditions or to the same ‘math gene’).  Thus, the authors concluded that absence of difference between the sexes in how these potentially causal factors influence their science achievement suggests that the possible sex differences in the high end of science performance “may be due to attitudes rather than aptitudes”.

The reference: Haworth, C., Dale, P., & Plomin, R. (2009). Sex differences and science: the etiology of science excellence Journal of Child Psychology and Psychiatry DOI: 10.1111/

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7 Responses to Boys, girls, science, math, and sex intellectual differences

  1. anomalous says:

    Of course, it could be that math genius doesn’t kick in until the testosterone rush of puberty hits.


    • No need to duck (yet) and I think that comment was actually very interesting. However, the authors found sex differences at age 9 but not at 12 (when some kids were likely already entering puberty). This age age related finding is contrary to your ‘teen testosterone’ hypothesis :-) . Thanks, Nestor.

  2. anomalous says:

    Most boys haven’t hit puberty by age 12 but most girls are in peak puberty at that age. Not a very apples to apples comparison.

    How about comparing abilities 2 years after peak puberty: 14 year old girls and 16 year old boys. That’d be a fair test.

    [ Altough, to be fair, I think most of them are into basic biology at that point ]

  3. DSC says:

    I teach high school sciences and I find two things:

    Girls age 15-18 often do as well or outperform the boys; it is often due to better work ethic and plain hard work, which the boys tend to have in less abundance.

    However, on questions involving critical thinking, the boys tend to do better in relation to spacial sense and diverse question outcomes. I have found this most evident amongst the top 10% of both sexes, the girls tend to miss out on the creative questions, the boys do better on them.

    Both of these are ‘on average’. In no way do I find that one sex outperforms the other overall, just that average differences do pop up in small ways.

  4. JulieL says:

    Speaking from a personal anecdotal experience, I happen to wonder though how represenitive what DSC states actually is. I find that science is often a naturally cultivated interested in boys, moreso than girls. So the population we are talking about are those whom cultivate these abilities, often driven by personal motivation to do so, not necessarily those whom actually HAVE the capacity to do so. Personally I never saw any application for math or science, yet I spent a huge amount of time reading books that were based in psychology and related fields, but didn’t recognize it at the time. Now that I”m older, I see the dots that were never connected before college. I find myself enjoying the sciences from a perspective I never had in my secondary education experience. Also another anecdotal observation of mine, many of my girlfriends, in their thirties, are regretting past degrees in areas such as interior design, just to go back to school for the sciences.

    So to me, I wonder, if it’s more that we are failing to connect to boys and girls the longterm, actual career application of the sciences, which is why there is a decrease in it’s fervor in the United States.

  5. Leah Daziens says:

    “Specifically, the authors reviewed teachers’ reports of the kids’ academic performance and examined the genetic and environmental predictors of “high science ability”

    While the “absence of difference between the sexes” is interesting, I am not sure how relevant this is to “science achievement”. I am not familiar with the British elementary & middle school curriculum, but in my limited U.S. experience, elementary school science grades reflect reading comprehension and memory skills rather than any “high science ability”. Additionally, science is not a high priority subject at the elementary school level and takes a back seat to reading and math.

    Now, I would think that following these same twins through high school and college would provide more relevant information on “high science ability”.

  6. twayne says:

    I came across this site in the course of research on women’s representation in science as a career. I do wonder (as have other scholars) what is the *purpose* or goal of such research? If there is a “science gene” (or neurocognitive differences between the sexes), where do we go from there? Would we just give up on girls? Or would we continue to encourage individuals (boys or girls) to pursue their interests and continue to make educational opportunities available?

    Also in my research, I have come across the argument that such research questions limit our view of what STEM (science, technology, engineering, math) careers are all about and what skill sets individuals actually need to succeed at higher levels. In other words, it cannot all boil down to spatial reasoning or another specific skill, but requires creative problem solving, imagination, interpersonal skills, writing skills, etc.

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