A new study reveals that sex differences in academic strengths are found throughout the world and girls’ relative advantage in reading and boys’ in science is largest in gender-equal countries.

Gender equality often draws attention especially in fields where women are underrepresented, such as high-status, high-paying STEM (Science, Technology, Engineering, and Mathematics) careers. Academic strengths, or a student’s best subject, strongly influence their field of study. Students with strengths in mathematics or science gravitate toward STEM fields, while those with a strength in reading gravitate toward other fields (e.g., journalism).

The research team analysed data from nearly 2.5 million adolescents in 85 countries over 12 years or in five waves (2006-2018) from the Programme for International Student Assessment (PISA). Their findings confirmed that girls’ strength is typically reading, while boys’ is typically mathematics or science. These patterns are found both across countries and time.

Most notably, sex differences in reading and science as academic strengths are more pronounced in countries with greater gender equality, such as Finland. Sex differences in mathematics, on the other hand, remained stable regardless of country-level gender equality.

"These results suggest that in more gender-equal societies, women may be choosing fields other than STEM based on their strength in reading. Increasing the share of women in STEM will require more than just boosting girls' math and science skills or advancing gender equality," says Doctoral Researcher Marco Balducci from the INVEST Research Flagship at the University of Turku, Finland.

The finding that sex differences in academic strength in reading and science are larger in gender-equal Scandinavian countries than in more traditional Middle Eastern countries –known as the Gender Equality Paradox – challenges the popular belief that sex differences are mainly driven by socialisation pressure.

"The common assumption is that as gender equality improves, traditional gender roles should fade, leading to smaller sex differences. But that is not what we found. Instead, our results align with recent research showing that sex differences either stay the same or even increase with more gender equality," says Balducci.

Professor David Geary from the University of Missouri notes that “Gender-equal, wealthy, and liberal countries offer more opportunities and allow greater freedom of choice. In these contexts, men and women make different decisions, leading to larger sex differences in various areas of life, including STEM fields.”

The research team encourages policymakers to prioritise mentorship opportunities for talented girls, as these may increase their likelihood of enrolling in a STEM degree programme. However, Balducci adds that “our study highlights that achieving parity between boys and girls could be challenging as broader factors, like sex differences in academic strengths, play a key role in determining sex disparities in STEM."