When traits are controlled by three or more genes, they are called polygenic traits and their inheritance is called as polygenic inheritance. Human skin colour is a classic example following polygenic inheritance as the skin colour is regulated by three pairs of gene. Polygenic inheritance is influenced by the environment as well and not just the polygenes. In this inheritance, the phenotype reflects the contribution of each allele and not only the dominant ones. The effect of each allele is (quantitative) and donot show uniformity.