Why Men Are Typically Taller Than Women

 Image courtesy of Helsingin yliopisto (University of Helsinki)

While studying genetic factors behind different traits in men and women, University of Helsinki researchers have identified a genetic variant on the X sex chromosome that accounts for height differences between the sexes. Sex cells, produced by male and female gonads, contain either an X or a Y chromosome. The fact that females have two X chromosomes and males only have one X chromosome must be taken into account when attributing difference in traits to variants on the X chromosome.

According to the study's head researcher, Professor Samuli Ripatti, "The double dose of X-chromosomal genes in women could cause problems during the development. To prevent this, there is a process by which one of the two copies of the X chromosome present in the cell is silenced. When we realized that the height associated variant we identified was nearby a gene that is able to escape the silencing we were particularly excited." The height variant identified influences a gene that is involved in cartilage development. Individuals that possess the height variant tend to be shorter than average. Since women have two copies of the X chromosome variant, they tend to be shorter than men.

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