A new study published in Nature suggests that the stem cells that allow our organs to grow “know” their own sexual identity, and this influences how they function. These findings could explain why the prevalence of some diseases, such as certain cancers, differs between the sexes. Beyond the obvious reproduction-related anatomical differences between males and females, many other organs also show sex specific characteristics, for example in the form of subtle differences in size or in their susceptibility to disease. The effect of hormones has been extensively researched, and can explain many of the differences. However, less is known about the potential impact of differences between the cells that created the organs themselves. The researchers found important genetic differences at the cellular level and also demonstrated how these differences impact organ growth, independently of circulating hormones. These findings could shed light on why some diseases prevail in men or women. …