Genetic Insights Reveal Y Chromosome's Role in Determining Male Height Differences

Height disparities between men and women are among the most visible biological differences in humans, with men typically standing about 13 centimeters (5 inches) taller. While sex hormones contribute significantly to this dimorphism, recent research highlights the crucial influence of genetics, specifically sex chromosomes, independent of hormonal effects.

A comprehensive study involving over 928,000 adults from biobanks in the U.S. and the UK has demonstrated that the Y chromosome plays a more prominent role in height determination than previously understood. Researchers analyzed individuals with sex chromosome aneuploidies (SCAs)—conditions where X or Y chromosomes are abnormally present, such as Turner syndrome (45,X), Klinefelter syndrome (47,XXY), XYY syndrome (47,XYY), and Triple X syndrome (47,XXX). They discovered that possessing an additional Y chromosome results in a greater increase in height compared to an extra X chromosome, regardless of circulating male hormones.

The key genetic factor involved is the SHOX gene located in the pseudoautosomal region 1 (PAR1) of both X and Y chromosomes. Although the X chromosome typically experiences inactivation (except for PAR1), genes like SHOX are partially active on both sex chromosomes, leading to higher gene expression levels in males with Y chromosome presence. This partial activity contributes to the observed height differences.

The study revealed that the effect of the Y chromosome on height is substantial—accounting for up to 22.6% of the average height difference between males and females—and consistent across diverse ancestries. Findings also suggest that pathogenic variants in the SHOX gene reduce height more significantly in males, further emphasizing its critical role.

This research enhances our understanding of the genetic basis for sexual dimorphism in humans and highlights how sex chromosome dosage impacts physical traits. Moreover, it offers insights into broader phenomena such as the differing prevalence rates of autoimmune and neuropsychiatric conditions between sexes.

Understanding these genetic mechanisms provides valuable perspective not only on height but also on biological differences influencing health and disease susceptibility across sexes. Source: https://medicalxpress.com/news/2025-05-chromosome-play-key-role-men.html