Why Are Men Taller Than Women? Science Has The Answer
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A recent study examining genetic information from almost one million individuals has helped explain why men tend to be taller than women.
On average, men tend to be about five inches taller than women. Although hormones have traditionally been the main reason for this, recent studies highlight the influence of genetics, especially sex chromosomes, as a key factor behind this persistent height difference. A thorough study featured in the Proceedings of the National Academy of Sciences (PNAS) examined genetic information from close to one million adults. Researchers utilised data from three major sources: the UK Biobank and two U.S.-based biobanks—MyCode and All of Us. Out of the 928,605 participants, 1,225 were found to have an unusual number of sex chromosomes, offering a unique perspective on the biological factors that impact height.
What the SHOX Gene Does
The study focuses on the SHOX gene, which is essential for determining height. This gene is found in a region called PAR1—pseudoautosomal region 1—that exists on both the X and Y chromosomes, allowing it to act similarly regardless of which sex chromosome it's on.
In females (XX), one X chromosome is mostly inactive, but genes in the PAR1 region, like SHOX, still work a little, though not fully. In males (XY), both the X and Y chromosomes use the SHOX gene completely, leading to higher activity of the gene.
By studying people with different numbers of sex chromosomes, like extra X or Y chromosomes, the researchers discovered that having an extra Y chromosome had a bigger impact on height than an extra X chromosome. This finding was consistent across various ancestry groups, showing a clear genetic effect on how tall someone is.
To understand how these chromosome differences affect height, the researchers used a statistical method called multivariate linear regression. This helped them consider factors like hormones, inactive chromosomes, and disorders such as Klinefelter and Turner syndromes. Their results showed that genetics from the Y chromosome accounts for a large part—up to 22.6 per cent—of the average height difference between men and women.
Matthew Oetjens, the lead researcher from Geisinger College of Health Sciences, highlighted the important role of the SHOX gene. He explained that because SHOX is located near the end of the sex chromosomes, it avoids being fully silenced in females, but only to some extent. In males, both the X and Y chromosomes work together to increase the genes' activity, which influences greater height.
New Insights
Although the SHOX gene explains about a quarter of the average height difference between men and women, scientists think other factors like sex hormones and unknown genes also contribute. Eric Schadt, a professor at Mount Sinai School of Medicine, said that using large biobank data helped solve a long-standing mystery. He added that while the gene's impact is small, it's an important step toward better understanding how humans grow.
Previous studies have found that over the last hundred years, men's height has increased faster than women's, making the difference between them even bigger. Social research also shows that women usually prefer taller men as partners. However, scientists warn that being taller might come with a higher risk of some cancers because taller people have more cell growth.
These findings improve our knowledge of why men and women differ in height and offer a starting point to study genetic reasons for other differences between the sexes. Researchers aim to keep exploring genes like SHOX and how they work with hormones and other body systems to better understand the complicated processes behind human growth and health.
First Published:
May 27, 2025, 15:28 IST
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