A DNA grandparent test can be used to determine if there is a biological relationship between a child and a grandparent. Often, in cases where an alleged parent is unwilling or unavailable to take a paternity test, the next best thing is to perform a direct comparison with a paternal grandparent through DNA testing.
Inherited Genes
During the testing process, genetic markers analysed from the grandparent will be compared to those of the child in question. If the results show that a biological relationship exists between them, this will in turn confirm that the biological parent of the child is the son/daughter of the grandparents since some of the genes inherited from the parent will be of course coming from the grandparents.
The testing process will determine what DNA if any is shared between the persons being tested and apply a statistical analysis to determine the biological relationship.
Y Chromosome DNA Test
In some cases, if both the child and the grandparent being tested are both male, it can be preferable to conduct a Y Chromosome test. This will confirm with 100% certainty if the child is from the same male lineage. This DNA test works on the basis that the Y chromosome is passed on from father to son and therefore remains intact through the direct male lineage.
Y-DNA testing involves looking at segments of DNA on the Y chromosome (found only in males). The segments that are examined are referred to as genetic markers and occur in what is considered “junk” DNA.
Taking the Test
When conducting a grandparent DNA test it is recommended to include the samples from both Grandparents when possible. We also recommend including the Mothers sample as well to assist in strengthening results.
There may be various reasons for requiring this test. However, the most common is when the parent in question is not available for testing either because they are deceased or alternatively they refuse to participate in the test. In the case of minors (16 – 18 years depending on country of location) you should check what permission from any legal guardians might be required.
If you are considering performing a DNA Grandparentage test, it is always recommended to contact your DNA testing laboratory in advance to discuss your case. They will be able to guide you on which DNA test is most appropriate for your case. Be sure to advise who is available for testing as this helps in the decision for the overall testing strategy.