Mendel and the Deviations.

Mendel made several significant contributions to the world of genetics. The first was his discovery of the recessive and dominant traits of "heritable traits" or genes, as we now call them. He found, by breeding pea plants, that certain genes were dominant over others, and that the characteristics of the dominant gene would take effect over the characteristics of the recessive gene. Another one of his discoveries is the Law of Segregation that states that …

…a blend of both parents. This presents a problem for evolution, since for evolution to happen by natural selection requires the presence of genetically based variation in the value of a quantitative trait. Yet if offspring tend toward the mean value of the trait for the two parents then, the necessary variation for evolution to happen would be lost. The inheritance of quantitative traits is typically viewed in terms of what is called polygenic inheritance.