Final answer:
Mutations occur spontaneously due to natural reactions within the body and can impact an individual's genetic material.
Step-by-step explanation:
Mutations generally occur spontaneously in response to conditions in the body or in the environment. The probability of a mutation at any given gene is between 1 in 10,000 and 1 in 100,000. While the probability that a specific point in an individual's genetic material will have a mutation is low, the probability that the totality of an individual's genetic material will have at least one mutation is much higher. Mutations can occur spontaneously without any exposure to environmental agents, as a result of natural reactions taking place within the body.