I often look at "outside sources." From one source explaining about mutations, it says, "A mutation is a change in a DNA sequence. Mutations can result from
DNA copying mistakes made during cell division, exposure to ionizing radiation, exposure to chemicals called mutagens, or infection by viruses. Germ line mutations occur in the eggs and sperm and can be passed on to offspring, while somatic mutations occur in body cells and are not passed on." (italics mine...)
So...somatic mutations occur but are not passed on while germ line mutations can be passed on to offspring.
Mutation