What Is DNA?

NA, or deoxyribonucleic acid, is the fundamental building block for an individual's entire genetic makeup–our hereditary blueprint passed on to us by our parents. It is a component of virtually every cell in the human body. A person's DNA is the same in each cell and it does not change throughout a person's lifetime. For example, the DNA in a person's blood is the same as the DNA found in that person's saliva. DNA also is found in skin tissue, sweat, bone, the root and shaft of hair, earwax, mucus, urine, semen, and vaginal or rectal cells. Parts of the DNA determine our physical characteristics, such as eye and hair color, height, and bone structure, but the DNA collected from the crime scene is for evidentiary purposes only and not to determine an assailant's physical characteristics.