Genetic variation is a fact that a biological system – individual and population – is different over space. It is the base of the genetic variability of different biological systems in space.Genetic variation is based on the variation in alleles of genes in a gene pool.It occurs both within and among populations, supported by individual carriers of the variant genes. Genetic variation is brought about by random mutation, which is a permanent change in the chemical structure of a gene.enetic variation is based on the variation in alleles of genes in a gene pool. It occurs both within and among populations, supported by individual carriers of the variant genes. Genetic variation is brought about by random mutation, which is a permanent change in the chemical structure of a gene.