The doorbell rings. Busy in the kitchen fixing dinner, Nancy's
dad calls out, "Answer the door, Nancy! My hands are full!"
Nancy opens the front door, and suddenly a bunch of people she
hasn't seen in 3 years pour into the house. Aunt Rita hands
Nancy a wrapped package and says, "Well, look at you! How you've
grown. And you've got such beautiful red, curly hair! It runs in
the family, you know. You look just like my grandmother!" Uncle
Michael adds, "And she's going to be tall, like her father. Only
9 years old, and she looks like a basketball player already!"
Nancy makes a dash to the kitchen, wondering, "Huh? Aunt Rita's
grandmother? Runs in the family? Basketball? What are they
talking about?" Genes (say: jeenz), that's what they're talking
about. Genes are the things that play an important role in
determining physical traits — how we look — and lots of other
stuff about us. They carry information that helps make you who
you are: curly or straight hair, long or short legs, even how
you might smile or laugh