New research suggests that one of the factors will be the SHOX gene, which is present in both men and women.
A new publication in the Journal of Human Genetics offers a new perspective on one of biology’s oldest questions: why are men generally taller than women? Researchers believe they have identified a key gene called SHOX which may explain much of the difference in average height between the sexes.
On average, men are about 13 centimeters taller than women. This difference has long been attributed to the influence of sex hormones like testosterone, which drive male growth during puberty. However, the genetic mechanisms behind this difference remain a mystery. Despite decades of research, scientists have been unable to identify a male-only “growth gene” on the Y chromosome, which is unique to men.
New research suggests that the answer may lie not in a male-only gene, but in a gene shared by both sexes which behaves differently in men and women. The SHOX gene, which is found on the X and Y chromosomes, is already known to regulate bone growth. However, until recently, the SHOX gene was largely dismissed as a possible explanation for height differences between the sexes, since both men and women have it, explains .
According to the authors, SHOX is expressed as significantly higher levels in men than in women, which means it is more active in promoting bone growth in male tissues. This elevated expression could explain much of the difference in height between the sexes.
Scientists performed a large genetic analysis of 928,605 participants, including 1,225 individuals with atypical numbers of sex chromosomes. The study found that people with an extra Y chromosome were, on average, 3.1 centimeters taller than those with an extra X chromosome, a difference that can only be explained by the activity of SHOX, since this is the only known gene related to growth on these chromosomes.
Additional analyzes revealed that defects in the SHOX gene caused a much greater height reduction in men (18.6 centimeters) than in women (8.9 centimeters), reinforcing the idea that the gene has a stronger growth effect in men.
The findings indicate that the SHOX gene likely plays a central role in height regulation, but the researchers warn that it may not be the only factor, noting that “other genes or RNA not yet identified in sex chromosomes can also influence height differentially between the sexes.”
