By this point in your life, you've heard plenty of explanations about why people look the way they look. Not everyone gets it right, but one thing human beings do really well is to observe patterns in the world around them. And patterns can tell you a great deal about heredity--how physical traits are passed down from parents to their children.

Let's say you're at a concert, and you notice that the bass player has a Mohawk. You know that the Mohawk, a hair style, is not an inherited trait. You may also be able to tell whether or not his hair is dyed or is naturally that color. You've observed nature enough to know that blonde, brown, black, and red are natural hair colors, but that neon green is not.

Families are great places to start observing patterns related to resemblance and traits. Notice that neither of the children in this picture is a perfect 50/50 blend of its parents' physical traits. The daughter has inherited her mother's hair color and her father's jaw line. The son has inherited his father's eye color.