Gene variation is very necessary for the process of natural selection. The genetic variation that occurs in a population can happen by chance, but in the case of natural selection it does not. Scholarly journal is a peer-reviewed journal in which scholarship relating to a particular academic discipline is published. The mutation is the small or large level change whereas variation is the change in the whole group. The mutation causes changes in genes always whereas variation is the change in either genes or general change. Genetic variation in humans means variation in gene pools that have occurred due to geographical, cultural, environmental, psychological and religious isolation. The total genes present in a particular population, i.e., species is known as "gene pool".