In this theory, aging is due to our inherited genes that come directly from our parents. Since the conception occurred, our body cells continue to divide and replication themselves. Since the division and replication are a life long precess at some point, for what ever reason, if cells division and replication can process incorrectly, leading to mutation of incorrect copy of DNA.Although the cause of this incorrect process are unknown, but researchers found that exposures to toxins, radiation or ultraviolet light, artificial ingredients, unhealthy life style, etc. can increase the risk of cells mutation and the cells copied incorrectly can mutate themselves, leading to accumulation of incorrect gene cells that trigger a chain reaction of an auto-catalytic nature in producing more and more incorrect gene cell, until it finally is brought under controlled, this processes can lead to aging. As an organism, the immune system tries to destroy or scavenger these mutated genes but at some points, it is over whelming, leading chronic age related diseases.