Molecular biology has provided several new tools, including restriction fragment length polymorphism (RFLP) analysis, the polymerase chain reaction (PCR), and DNA fingerprinting, that are becoming increasingly common in the determination of genetic traits of individuals. These methods of analysis are all based on the principles that since the DNA of an organism contains the genes that code for all of the physical characteristics of a specific individual and since each individual (with the exception of identical twins) has a unique combination of genes, a DNA sample isolated from an individual can be used to predict physical traits or to actually identify the individual out of a group.