For example, the hydrate and the skin color trait. Now, to demonstrate what we mean by polygenic inheritance, let's begin by assuming that the skin color trait in humans is controlled by three gene pairs. So we have gene pair A, we have gene pair B and we have gene pair C. Let's suppose that these three different gene pairs are unlinked genes and what that means is they're located on different homologous chromosomes. So let's suppose we have homologous chromosome pair number one, homologous chromosome pair number two and homologous chromosome pair number three. Now, in pair number one we have the A traits. So this can either be a upper case A or lowercase A.