(a) The germ cells of sexually reproducing populations are made in specialized reproductive tissue. Change in non-reproductive tissues, on account of acquired traits, cannot be passed on to the DNA of the germ cells. Therefore, experience gained or traits acquired during the life-time of an individual not inherited.

(b) The billions of human beings living today all belong to one species : Homo sapiens. As in all species, there is variation among individual human beings, from size and shape to skin tone and eye color. But we are much more alike than we are different. We are, in fact, remarkably similar.

(c) Gene transfers from generations to generations. Every generation carry both traits from the previous generation and new traits. These new traits are basically the variation that appears in this generation. Similarly, these differences or variation stays and move on from one generation to another.

For example: birth of a white child to a beige color parents because the grandfather of the child has white skin color.