Fingerprints are unique to each individual. Methods of recording and matching fingerprints have allowed police to correctly identify many criminals. Genetic scientists have recently developed another tool for identification based on the uniqueness of each person's genes. Genetic differences account for the large variations we see among individuals. This genetic variability is expressed in obvious traits like hair color and genetic disorders such as hemophilia. However, more genetic variability is hidden from view and can only be detected by directly studying the deoxyribonucleic acid (DNA). Each human has approximately 100,000 genes in the chemical form of DNA. The genetic information coded in the genes varies greatly between individuals. Thus, no two humans, except for identical twins, have exactly the same genetic code. A description of a person's DNA that is detailed enough to distinguish it from another person's DNA is called a DNA or genetic "fingerprint." In...