How Accurate Is A Grandparent DNA Test?

how accurate is a grandparent dna test

A paternity test is called an “exclusionary” DNA test. What this means is that the result provides a yes or no answer to the question if a man is a biological father of a child. A Grandparent DNA test, since it does not test the father and child directly, has the results shown as a probability that the relationship exists. This probability is expressed on the DNA results report as a percentage. This percentage ranges from 0% to 99.99%+.

Testing for this type of biological relationship is based on the statistical probability that two or more people are related by bloodlines as grandparent and grandchild. The industry standard for testing is 16 alleles (aka genetic markers) in an attempt to arrive at a conclusion of whether a grandparent/grandchild relationship can be verified. The challenges and limitations with this standard is that when using so few genetic markers, it is very difficult to arrive at a conclusive result. This is because a grandparent only shares up to 25% of the same DNA with their suspected grandchild. All humanity shares 99.9% of the same DNA, which means that only .10% can be used to confirm or deny the relationship.

When only 16 markers are being considered, there is a very good possibility that an inconclusive result will be reported. Even worse, a false negative or false positive is also a potential outcome. We strongly believe that there are just not enough genetic DNA markers tested in a standard test to feel confident about the results.

This is why our DNA testing uses up to 50% more alleles than other companies. The DNA sample of the mother can be included at no additional charge. The results we provide to you, which shows the probability of that the grandparent and grandchild are biologically related, as stated on the report, is 100% accurate. The testing process that is used for our DNA samples is the exact sample process, and the same results, whether for a legal grandparent DNA test, or our at home grandparent DNA test.

Often, we are asked if the home test results can be used in court, since the results we show are the same. DNA test reports are unable to be submitted into evidence in court if they are not

  1. Tested and reported from an AABB accredited lab;
  2. Collected from an independent DNA collector completing a chain of custody to verify the identity of those being tested.

Our testing results fit both of these requirements, for all DNA test we perform.

In our grandparent DNA testing process, we begin with a base of 24 genetic markers. If we are not able to obtain a strong enough finding at that level we will automatically upgrade your test, up to 46 markers if necessary, until the lab is satisfied that the strongest result has been obtained. Grandparent DNA test results are always reviewed by a Ph.D., who verifies the conclusion and signs the report.

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