The first scientific discovery is the epigenetic variation where it describes the deviation in the chemical tags that attach to DNA which affect how genes are read. Theses tags are called epigenetic markings that act as switches that control how genes can be read. Another essential discovery on human variation is the genetic variability, which measures the tendency of individual genotypes in a population to become different from one another. In addition, the variability of a trait is how much that characteristic tends to vary in response to environmental and hereditary influences.