Grandfather to Grandchild testing to Establish Biological Links

12 Aug 2017

There are different types of Relationship tests that can help solve the question of paternity and one of them is the Grandparent DNA test.  The origins of the DNA markers of father are from both the grandfather and the grandmother.  It is therefor possible, by submitting their DNA, to determine if the child in question has been issued from their line of DNA.  In other words to determine if this grandchild is indeed the child of the grandparent’s child.  This  is extremely useful when the father is not available for testing and paternity needs to be determined.

Is testing one Grandparent enough, or is it better to test both?

Scientifically you can test a grandchild against just one grandparent and a probability of biological relationship is drawn based on the similarities of their DNA but unfortunately, with this test, it might not be enough.  Most DNA testing companies would always suggest that you test both grandparents.   There is a possibility that the grandchild might have inherited parts of the father’s DNA that he inherited from one grandparent mostly rather than the other.   When only one grandparent is available and the persons in question still want to proceed with the test because it’s the only option, then it is highly suggested the mother also participates in order to enhance the precision.  Participants proceeding with a one grandparent test should keep in mind there is a possibility of a false negative outcome.  Meaning that even though the result states that there is no biological relationship, the possibility that there is one still exists.  For this reason it is always better to test both grandparents in order to have full view of all possible genetic marker combinations.

What does a Grandparent DNA test result (Missing persons report)

Children inherit the DNA markers from both their mother and father and in turn the child’s father has also inherited his DNA markers from his parents too (Grandfather and Grandmother).   So if a father’s DNA should match to a child’s DNA in all genetic markers in order to be the biological father, then also the child should have a match in each marker from both grandparents as well.  When both grandparents’ samples are submitted for testing, it is possibly to draw a missing persons report.  A probability of paternity is drawn based on the comparison of the grandchild’s DNA against all possible combinations that can be issued from the tested Grandparents.  If there is a match then it is confirmed that a biological link exists.

Grandparents and Y Chromosome testing

When only one grandparent is available, testing is not highly recommended as chances are the a false negative result could be drawn.  If the only grandparent available happened to be the grandfather from the paternal side of a male grandchild then a Y Chromosome test can be carried out instead.   By comparing the Y Chromosomes of both participants this test can determine if the is a direct male link in between the two males participants.   It is essential that the could have not being any possible involvement of another male relative  as his Y Chromosome would also be the same and this would falsify the result.  The Y Chromosome is passed on from male relative to another, generation after generation.  If two males are linked through this line then their Y Chromosome should match.

It is always highly recommended to consult with a professional genetic consultant before ordering your test in order to ensure that you are choosing the right test and the correct participants to ensure that the result will give you the right answer you are looking for.