DNA (deoxyribonucleic acid) is the genetic blueprint that determines a person's biological characteristics. DNA is located in every nucleated cell of the human body. Upon conception, a child inherits one half of his DNA from his mother and one half from his father. The unique combination of DNA, once analysed, will match that of the biological parents. When a paternity test shows that a child's DNA does not match that of the alleged father, he is excluded 100% as the biological father of the child. When the child's DNA does match that of the alleged father, we can prove a probability of 99% or greater for paternity. To arrive at a probability of paternity, human cells are first extracted from the tested parties. In the case of in-home sample collection, cheek cells are collected from the mouth with a buccal swab. In the laboratory, these cells are removed from the swab. The DNA from these cells is then extracted, and cut into sample fragments with enzymes. These fragments are placed into a gel matrix, where an electric current drives the fragments across the gel. Later in the process, these fragments are exposed to a labelled DNA probe. This probe recognizes and binds to a unique segment of the person's DNA. Where this probe binds to each person's DNA is the key to establishing relationships. A film is developed which will reveal black bands where the probes bound to each individuals DNA. The pattern of a child is unique - half matches the mother and half matches the father. If it is revealed that the band patterns of the alleged tested father DO NOT match that of the child, that person can be conclusively excluded as the child's father. If the patterns DO match, the probability of paternity begins to grow. This entire process is repeated several times independently in a comprehensive paternity test. Many different probes, producing many different band patterns, are revealed. The more probes that are used; the more definitive the results can be.