Rates of Spontaneous Mutation (Drake et al., 1998)[1] says that a human's genome accumulates around ~64 new mutations per generation through meiosis alone. Those mutations are propagated into every cell of the newborn baby. Over a lifespan, all cells in the body will mutate at a rate proportional to their division rate, leading to thousands upon thousands[2] of uncorrected mutations per individual, among the trillions which are ultimately corrected by DNA polymerase[3].