Chromosome pair 23 are the sex chromosomes and are responsible for determining the gender of a human. The large chromosome is an
X chromosome, and the small chromosome is the Y chromosome. If there are two X’s, then the individual is a female. If there is an X and Y, then the individual is a male.
More commonly, an X chromosome will die and get replaced by a Y chromosome (all humans start off as females). When this occurs, the substitute Y chromosome causes changes in the zygote to occur; they begin developing male genitalia (i.e. penises, testicles, prostates, etc.).
