During conception, the father’s sperm cell and the mother’s egg cell, each containing half the amount of DNA found in other body cells, meet and fuse to form a fertilized egg, called a zygote. The zygote contains a complete set of DNA molecules, a unique combination of DNA from both parents. This zygote divides and multiplies into an embryo and later, a full human being.

At each stage of development, all the cells forming the body contain the same DNA—half from the father and half from the mother. It is this fact that enables scientists to use a variety of sampling methods for DNA testing. We can take samples at virtually any stage of development and from any part of the body—and still obtain the same results, because these samples contain the same DNA.

Once the laboratory has received the samples from the tested parties, testing process can begin. The testing process used is Polymerase Chain Reaction, or PCR, combined with the Identifiler analysis system. The DNA must first be isolated from the specimen, which requires the removal of any proteins and other cell components.

Once isolated, the DNA is placed into a thermocycler with 16 florescent primers which allow the Identifiler system to locate specific fragments of the DNA. Within each cycle of the thermocycler, the primer finds the specific fragments and amplifies those areas. After amplification, the DNA is placed in an ABI Prism Genetic Analyzer, which performs capillary electrophoresis. At this point, the DNA loci, or fragments, are mapped and a genetic profile is created. The individual profiles are then analyzed and compared and a paternity probability is calculated.