If you’re left-handed, it means it is easier for you to use your left hand to do things like writing, brushing your teeth, catching or throwing a ball, and lots of other things. Only about 10 percent of people—just one in every 10—are left-handed. If you’re one of them, you are part of a rare and special group!
Scientists think handedness, or the hand we prefer to use, is affected partly by our genes. Genes are tiny little parts of our cells that contain special instructions called DNA that make us who we are. We get our genes from our parents. Different genes have instructions that determine the color of our eyes, whether our hair is curly or straight, how tall we are, and much, much more. Whether you are left-handed or right-handed might also be decided by your genes.
Scientists aren’t sure. Gene mutations (myoo-TAY-shuns), or changes or mistakes in our DNA, in one group of genes might play a role. Another idea scientists have is that before we are born, when we are still inside our mothers’ bodies, hormones (body chemicals that help us grow) may make changes to our baby brains that influence whether we are left-handed or right-handed. You can see we still have a lot to learn!