23 Pairs A typical person has 23 pairs of chromosomes (46 total) in almost every cell. The 23rd pair, also referred to as the sex chromosomes, contains genes that determine the sex of the developing person. If the 23rd pair is XY, then the zygote will develop into a male; if XX, it will become a female. Can you tell what genetic sex is represented here? (See bottom of column for answer.)