Your body has about 200 types of cells. Each cell has a job. Some help you see. Some help you hear. Some absorb food. Some transport oxygen. Some carry messages from your brain (also made of cells) to other parts of your body. All these cells need to know what to do and how to do it. That’s DNA’s job. It’s the Big Boss of your body.

God designed your body—and, for that matter, your cat’s body—to work according to DNA’s very specific blueprint. (A “blueprint” is a drawn-out design you might use while building a house.) DNA is very small—so small it’s hard to find the right words to describe how small it is! If you unwound all the DNA in just one of your cells, it would stretch six feet long. If all the DNA in your whole body were linked together, it would stretch to the Sun and back—around 600 times!

Do you look a little bit like your dad and a little bit like your mom? That would make sense, because you get half your DNA from each of your parents. Just think of how different one person can be from another person. The world seems to have an endless variety of people! That’s DNA at work. But here’s something surprising: When it comes to DNA, people are all 99.9 percent alike. That itty-bitty fraction of a percent makes all the difference in the world. When God planned out what you would be like, he did it on purpose—down to the teeniest, tiniest details. And all those details started with something way too tiny to see—your DNA. This set of instructions is all over you! A scientist could find it in your spit—or in a single one of your skin cells.