Here's why:

* Somatic Cells: These are all the cells in your body that aren't involved in sexual reproduction. They have a full set of 46 chromosomes, which are arranged in 23 pairs. This is called being diploid.

* Germ Cells: These are the sex cells (sperm and egg). They have only half the number of chromosomes, 23 in total, which is called being haploid. This is because when a sperm and egg fuse during fertilization, the resulting zygote has the full complement of 46 chromosomes.

So, all your skin cells, muscle cells, nerve cells, etc. have 46 chromosomes, while your sperm or egg cells have 23.