Here's why:

* Somatic cells: These are the cells that make up our body tissues and organs. They have two sets of chromosomes, one set inherited from the mother and one from the father. This is called diploid.

* Gametes: These are sex cells (sperm and egg) that contain only one set of chromosomes. This is called haploid.

So, while a normal human cell has 46 chromosomes, sperm and egg cells only have 23.