Do you ever read detective books, or watch detective shows on television? Then you probably know that one of the ways the police solve crimes is by finding fingerprints the criminal left behind.

Let's say there was a burglary at a house one night. The police came to investigate and found a clear set of "prints" on the dining room table. They used special powders and other equipment to make a copy of the prints. Then they checked them against a huge supply of other fingerprints stored in a computer system. The prints from the house matched one set in the computer's memory bank. The criminal had been caught -- and fingerprinted -- before. So the police knew who to look for.

This system works because each human being has unique fingerprints. No two people have the same patterns of curves and lines on the tips of their fingers. Even identical twins have slightly different patterns.

Your fingerprints are yours and yours alone. Five or six months before you were born, the patterns were already in place. They'll stay exactly the same as long as you live. Even if you burn your fingers, the skin will heal over and regain the same set of prints you had before the injury.

When you are a growing fetus, or unborn baby, the way you grow depends on a "blueprint" in your cells. This plan comes from tiny parts of cells from your mother and father. These tiny parts of the cells are called genes and chromosomes. They determine things like your hair color, the shape of your earlobes, and whether you're a boy or a girl. Your genetic blueprint also helps determine the way your fingerprints look.

When you're in your mother's womb, your environment, or surroundings, also influences the way you grow. Before birth, you may have pushed up against the wall of your mother's uterus as your fingerprints were forming, and bent them a little this way or that. There may have been small changes in the blood supply coming into your body. Even tiny variations like these are enough to turn each person's fingerprints into a special "signature" unlike anyone else's.

Why do you leave fingerprints on things, even when your hands are clean? That's because there are tiny sweat glands on your fingertips that constantly produce enough moisture to leave prints on anything you touch. If you leave your fingerprints -- especially jam prints or ink prints -- on the refrigerator or a newly polished table, your parents may get annoyed.

But the fact that your fingerprints are unique can also be used to protect you. Your parents have probably told you that there are people in the world who might try to harm you. You may be reminded of this unpleasant fact when you see pictures of missing children printed on the paper bags at the grocery store where you shop, or on milk cartons. No one likes to think about danger, but it's important to be aware that it exists, and to learn how to avoid it.

In 1982, a new law set up a national computer to help keep track of missing children. And many programs have been started to teach kids and parents how to stay safe. Some experts think that it helps if parents have their children's fingerprints taken, and give the prints to the police to put in a file. Criminals may think twice about doing harm if they know that children could be easily identified from their fingerprints. Already, millions of kids have taken part in this nationwide program. Ask your parents if they think that fingerprinting might be a good idea in your community. Tips for Parents

Parents in the Washington area are close to a tremendous resource to help them protect their kids. The national Center for Missing and Exploited Children opened here in 1984, with a $3.3-million grant from the Justice Department. The center's mission is to help parents, law enforcement agencies, schools and community organizations concerned about missing children. As many as 1.5 million children are reported missing each year, with 5,000 of them abducted by child molesters, according to the Justice Department.

The center acts as a clearinghouse for data on missing and exploited children, and offers advice to families in which these kinds of tragedies have occurred. It offers programs designed to teach children safe behaviors in public places like supermarkets, malls and the playground. The center is located at 1835 K St. NW, Suite 700, Washington, D.C. 20006; 634-9821.