Mutations that occur in body cells (also called somatic cells) are not passed on to offspring because they do not affect the germ cells, which are the cells that give rise to sperm and egg. Here's why:

* Germline vs. Somatic Cells: Our bodies are made up of two main types of cells:

* Germ cells are the specialized cells responsible for sexual reproduction. They are the only cells that can transmit genetic information to the next generation.

* Somatic cells are all the other cells in the body that make up tissues and organs.

* Inheritance: Only mutations in germ cells are passed on to offspring. Mutations in somatic cells occur after the germ cells are already formed.

Example: Imagine you get a sunburn. This damage to your skin cells is a mutation, but it won't affect your children because the germ cells that form your children's DNA were already established before the sunburn.

Key Point: The genetic material in germ cells is what gets passed down to offspring. Somatic cell mutations occur later in life and don't affect the genetic material passed on to children.