Sex chromosomes responsible for much more than determining sex, study shows

Human sex chromosomes originated from a pair of autosomes, the ordinary or non-sex chromosomes that contain the majority of our genome and come in identical pairs. That ancestral pair of autosomes diverged to become two different chromosomes, X and Y. Even though X and Y have grown apart from each other and taken on unique functions—namely, determining sex and driving sex differences in males and females—they also retain shared functions inherited from their common ancestor.