Genetic testing (DNA) to prove paternity may be done in appropriate cases. A child inherits its genetic profile from its mother and father. The genetic material present in a child which is not present in the mother must have come from the biological father.

• Appointments are set for the mother, child and alleged father to appear at the testing facility for genetic samples to be taken. (NOTE: separate appointment times are used so the parties aren't at the facility at the same time.)
• At the test site, identification of each of the parties is done. This usually includes checking a photo-I.D. (such as a driver's license), taking a photograph, taking a thumbprint, and having the party sign a document.
• Samples are obtained for testing. This may be done by drawing blood or by using a swab to lightly scrape the inside of the cheeks.
• The samples are tested for several different genetic indicators.
• The results of each test are compared. There will be some indicators that both the child and mother have in common. There will be some indicators that the child has that the mother does not have. All of these "extra" indicators in the child must have come from the biological father.
• If, when the alleged father's sample is examined, it lacks any of the child's "extra" indicators, the alleged father will be eliminated (excluded) as a possible father.
• If, when the alleged father's sample is examined, it has all the child's "extra" indicators, the alleged father is not eliminated and could be the biological father.
• If the tests show the alleged father could be the biological father, the testing laboratory will calculate a probability of paternity. The probability of paternity in DNA test results will usually be well above 99%.