Every cell in the human body needs to know how to develop, function, and survive. The sets of instructions that tell our cells how to work are called GENES. 

Our genes are written in a code called DNA. DNA is made up of 4 letters: A, G, C, and T. The order of these letters provides our cells with instructions for building and maintaining our bodies. This is similar to how the letters of the alphabet appear in a certain order to make words and sentences.

Humans have about 20,000 genes! Each person has 2 copies of most genes—1 copy from each biological parent.