What's color blindness?
To understand what causes color blindness, you need to be cool with cones and what they do. No, not ice cream cones! We're talking about the cones in your eyes. At the very back of your eye is the retina. It's about the size of a postage stamp, and it contains millions of cells that are sensitive to light. Some of these cells are called cones. Cones let you see color by combining the three main colors (red, blue and green) to make thousands of colors, from the orange of your macaroni and cheese to the turquoise of a tropical fish.
Even though many people think that being color-blind means a person can't see any color, this isn't true. Very few color-blind people see life the way it is on an old black-and-white TV show. Instead, most people who are color-blind just have a hard time telling the difference between certain colors.
If you don't have the correct chemicals in the cones, they may not let you see the right number of main colors. Most people who are color-blind aren't able to see red or green. For example, when a kid who is color-blind looks at a green leaf, he sees a leaf that's either a neutral color (like a light tan) or a shade of gray.
Color blindness is almost always an inherited (say: in-her-ih-ted) trait, which means it's carried in the genes (say: jeenz). (Genes are what you get from your parents, and they are responsible for everything from your hair color to your height.) Color blindness is much more common in boys than in girls. In fact, if you know 12 boys, one of them is probably at least a little color-blind! Sometimes people can become color-blind after having certain kinds of eye diseases, but this is rare — especially in kids.
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