»  How accurate is DNA testing for the purposes of determining paternity?  (Back)

DNA testing is the most accurate method available for determining paternity. All human beings receive half of their genetic profile from their biological mother and half from their biological father. Once samples are submitted by all participants, testing begins with extraction of DNA from those samples. The analysis is then made by using a set of well-characterized (highly polymorphic) DNA markers. These markers are specifically chosen for their ability to display an array of differences throughout the human population. Many of these markers are the same used by police and government agencies use for the identification of convicted criminals in the CODIS DATABASE.

The markers are detected by using a chemical process called polymerase chain reaction (or PCR). The final result yields a unique genetic pattern (genotype) for each person being tested. The patterns are then compared. If the alleged father's genotype displays differences from the child's genotype, then he cannot be the biological father and is therefore excluded from being the biological father of that child with a 100% probability of exclusion. If the alleged father and child share DNA patterns on all the tested markers, the alleged father includes as the biological father with a greater than 99.9% probability

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