Genes are the biochemical units of heredity that form the chromosomes. The genes are essentially the segments of DNA molecules that contain the code for particular peptides or proteins which then determine who we are (at birth and what we can become – let’s not forget about the importance of environment, but the genes give us the starting point). Our eye color, skin color, hair color and type, athletic potential, “smarts” potential, etc., are all influenced at this level.