How Is Paternal DNA Testing Done?

Paternal deoxyribonucleic acid (DNA) testing is a procedure that establishes whether or not a certain individual is, in fact, the father of another individual. This test can be accomplished as early as during pregnancy, or at any later time in life. In most instances, the paternal DNA test requires DNA samples from the mother, the child and the presumed father, and can produce results within days.

The DNA of a child is a combination of the DNA from the mother and the father. All portions of the child's DNA strand will be identical to either the mother's DNA or the father's DNA. Without the mother's DNA, it is still possible to determine whether an individual is a child's father if he shares segments of the "Y" chromosome.

In the process of paternal DNA testing, samples are collected from all necessary individuals. In a prenatal test, this requires a sample from the fetus, as well as the mother and potential father(s). While collecting a sample of fetal DNA can be accomplished by isolating the fetal DNA material found in the mother's blood or urine, the amount of fetal material found in the bloodstream is higher. With older children and adults, DNA samples are taken from swabbed saliva from the inside of the cheek.

Once DNA samples are collected, the genetic markers are compared to one another. First, the DNA from the child is compared to the DNA of the mother, and the segments of the DNA that match the mother are removed from the sample. The remaining segments are then compared to the prospective father's DNA. An individual who shares paternal DNA markers with the child is presumed to be the father. In the event that the DNA markers do not match, the individual is not the child's father.