Female (XX) mammals inherit one X chromosome from each parent, but males (XY) receive an X from their mother and a Y sex chromosome from their father. X and Y chromosomes determine not only the ...

But that doesn’t always apply when it comes to categorizing people by their sex chromosomes. "You either have XX or XY chromosomes," Rep. Nancy Mace, R-S.C., wrote Feb. 20 on X. "Those are the ...