Answer:
An alteration in DNA that occurs after conception. Somatic mutations can occur in any of the cells of the body except the germ cells (sperm and egg) and therefore are not passed on to children. These alterations can (but do not always) cause cancer or other diseases.
Step-by-step explanation:
when a skin stem cell harbors a cancer-driving mutation, it becomes more likely to generate two specialized skin cells when it divides. Over time, the mutated skin stem cell fails to renew itself and turns into cells that eventually slough off, allowing the skin to expel mutated cells as needed.
Errors in DNA copying during cell division and development can cause new mutations — called de novo mutations — at any time from the moment of conception. Mutations that occur in the germ line — the cells that develop into sperm or eggs — can be passed on to the next generation and, perhaps, cause disease in children.