"You either have XX or XY chromosomes," Rep. Nancy Mace, R-S.C., wrote Feb. 20 on X. "Those are the options." Most commonly, a person is born with two X chromosomes (female) or an X and a Y (male).

Human biological sex is determined by the sex chromosomes X and Y. In most cases, females possess two X chromosomes, while males have one X and one Y. However, there is some evidence that the Y ...

Affected populations: Norrie disease is an extremely rare, inherited genetic disorder ... two X chromosomes (XX) — one of ...

Since females have two X chromosomes ... also referred to as Jacob’s syndrome, occurs when a male infant is born with an extra Y chromosome. Some symptoms include being tall and having a ...

"While these may seem like two sides of the same coin ... risk factors for autism may be linked to the Y chromosome. Autism ...

The modification successfully induced blood chimerism—a condition where an individual has two sets of genetically different cells, in this case one with and one without the Y chromosome—in 81 percent ...

X inactivation only occurs in cells with multiple X chromosomes, which explains why almost all calico cats are female. X inactivation exists in two different forms: random and imprinted.