Why can mutations in body cells cause cancer without being inherited by children?

Mutations in body cells, known as somatic mutations, do not cause cancer that is inherited by children because they occur in non-reproductive cells.1

In the context of human pathology, genetic alterations are categorized into two distinct types:

• Somatic mutations: These occur in body cells (such as skin or lung cells) and affect only the progeny of that specific mutated cell. Because these mutations are restricted to somatic tissues, they cannot be passed to offspring. These mutations are often acquired through environmental factors like ultraviolet radiation or chemical exposure, and they are the primary cause of sporadic cancer.12
• Germ line mutations: These occur in reproductive cells (sperm and eggs). Only mutations present in the germ line can be inherited by children.1

While most cancers are sporadic and arise from somatic mutations, some individuals inherit a predisposition to cancer if they are born with a mutation in a tumor suppressor gene or a DNA repair gene. In these familial cases, the inherited mutation itself does not cause cancer, but it makes the individual significantly more susceptible to developing the disease through subsequent somatic mutations later in life.23