A DNA grandparent test can be used to determine if a grandparent or grandparents are related to a child whose alleged parent (normally the father) is their biological parent. This type of test is mostly requested when the alleged parent is unable or unwilling to participate in a DNA Paternity Test. Of course, where the alleged parent is available, the best course of action is to perform a direct comparison through DNA paternity testing.
When performing a DNA grandparent test the genetic markers analysed from the grandparent (s) is compared to that of the child in question. If the result indicates a biological relationship between them, then 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.
When conducting a Grandparent test it is recommended to include the samples from both Grandparents when possible. Alternatively we always recommend including the Mothers sample as well to assist in strengthening results.
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.
In some cases, instead of direct STR analysis, other forms of testing may be applicable. For example, if the child is male and the grandfather is available for testing, then a Y Chromosome DNA test is preferable as it will confirm that the child is from the same male lineage with 100% certainty. 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.
If you are considering performing a DNA grandparentage test, it is always recommended to contact your DNA laboratory in advance to discuss your case. They will be able to guide you on which DNA test is most appropriate for your case. Also ensure to advise who is available for testing as this helps in the decision for the overall testing strategy.
There may be various reasons for requiring a DNA grandparentage 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 may be required.