Grandparent Testing

41 Marker Grandparent DNA Test

When an alleged father is not directly able to be tested, at least one of his parents are likely to help. Biological parents contribute equally to their son’s DNA, so that one-half of his DNA comes from each parent. When the child becomes a father, he in turn contributes to half of his child’s DNA. Therefore, half of the grandchild’s DNA comes from the grandparents, through the son.

Bio-Gene’s Grandpaternity DNA Test determines the likely statistical probability that a person is the biological grandparent of a child. This DNA test requires the participation of at least one possible grandparent and the child.

Unlike a DNA paternity test which will always provide a conclusive result, relationship tests are different. When a grandparent test is conducted, our DNA testing laboratory will determine the genetic profile of the alleged relatives. Based on the type of genetic material exhibited by each person, an index is determined. If the index is less than 1.00, this indicates non-relatedness. If the index is greater than 1.00, this indicates that the two tested individuals are more likely to be true biological grandparent. The higher the value of the index, the greater the likelihood that the two individuals are true biological relatives.


Private At Home Grandparent DNA Testing

Bio-Gene will only perform private peace of mind, at home grandparent DNA tests using an accredited 41 marker basis. While much higher than the industry standard, we have found that it is in our clients best interests to perform a higher marker test. We believe you should get the right answer the first time you test. Please take a moment and review our case studies below to learn about why our 41 marker tests are the most accurate tests available.

Read why Bio-Gene will not perform 16 marker testing for any Grandparent DNA testing.

The best method of DNA collection and testing is to use a buccal swab, which is similar to a “Q-tip”, which has been rubbed on the cheeks of the mouth of those being tested. Sometimes it is not possible to obtain a buccal sample. We are able to test alternative samples, normally at no extra cost. The sample must have been stored in a paper envelope or breathable environment. The sample should not have been stored in a plastic bag at any time.

Some of the alternative samples that can usually be tested include:

Amniotic Fluid

Cups / Bottles

Feminine Hygiene


Bandaid (Used)

Dental Floss



Chewing Gum


Hair (With Root)


Cigarette Butt

Electric Razor

Hat (Well Worn)


Condom (Used)

Envelope / Stamp




Grandparent DNA Test – 41 Marker

Using our 41 marker specialized testing process we are able to take a statistical approach by testing only one grandparent and child, and in most every case obtain a conclusive result. In the event that it is necessary to test another grandparent to make certain we have conclusive results, neither the child or orginal testing grandparent will need to retest.  The statistical approach uses this approach: we all have four grandparents and each has donated 25% of our genetic profile. The calculation determines if it’s more likely that a grandparent and child share 25% in common or share what two random unrelated people would share in common. When less people are tested, more markers are needed. The following case studies are provided to demonstrate the difference between results from a 16 marker grandparent test and a 41 marker grandparent DNA test.


Case 1

A grandmother and child are compared to determine if her son could be the father. After testing 16 markers, it is found that there was only a 30.0% (69.20% unrelated) probability of relationship. We report any probability less than 80% as inconclusive, to match our legal tests. Scientifically, you cannot draw a conclusion from the information when it is below 80%. We asked for the mother’s sample and tested with the 16 maker test. The results were also inconclusive with a probability or relationship of 43.88% (56.12% unrelated). After testing 41 markers, the probability of the grandmother being related dropped to 0.01%, meaning that she was 99.99% probable to be unrelated to the child. He son was not the biological father.

Case 2

In another grandmother and child comparison with 16 markers, the results were found to be a probability of relationship of 27.09% (72.90% probable to be unrelated). The mother was unavailable for testing and we proceeded with the 41 marker test. We found the probability to be 99.70% in favor of a relationship with the child. This illustrates the power of additional markers being testing, and why our inconclusive level is set at 80%. The 16 marker test is simply not strong enough and, at times, can produce misleading results as proven by this case.

Case 3

This grandmother and child DNA comparison with 16 markers produced a nearly equal probability of being related or unrelated at 48.85%. After testing 41 markers, the probability increased to 87.26% probability of relationship. This was sufficient to demonstrate a biological relationship.

Case 4

In this case, the alleged grandfather, child, and mother were tested. The probability of relationship at 16 markers was 57.56%, which is inconclusive. The probablity increased to 99.99% after testing the three participants with the 41 marker test.

The conclusions that can be drawn from these cases is that a 16 marker DNA test will not produce conclusive results, in most cases, when performing a grandparent DNA test.


What the DNA testing results look like

Due to performing a high marker test, Bio-Gene is able to deliver results that show conclusive results in almost every single case we handle. The sample result below show how the genetic code is listed (left hand side), and how the results are given (upper right hand side). In this case we were able to determine beyond a reasonable doubt that the son of the paternal grandparent in question was NOT the biological father. In deal with probabilities, 90% or greater is commonly accepted as proof for or against biological relationships. In the even that the son of the grandparent being tested was the father of the child, the results would have shown the probability that they WERE kin.

Grandpaternity Kinship Report:

Grandparent test

The results are clear, understandable, and are definite. Testing results are available in a secure manner 24 hours a day, and are always kept confidential. We are able to provide answers to your paternity questions in a conclusive manner in over 99.99% of the cases we accept. Our Case Managers are also available during regular business hours to review you results with you if you have any questions at any point.

How to Order a Grandparent DNA Test

To order your Grandparent DNA test kit, please complete the order form below and you will be taken to our secure server. Our prices can be found by selecting the test of your choice, the number of people testing, and your payment preferences when providing the information that is relevant to your particular case.

When ordering a grandparent test you may choose to use a testing kit from Bio-Gene DNA or build your own kit. This may be especially helpful is you are using alternate samples, or do not wish to the kit to arrive due to time constraints.  To learn about using your own DNA testing kit, please click HERE.

If you chose to use a Bio-Gene kit, you will choose the shipping option that is right for you. Once your kit is mailed, you will be provided a tracking number to be able to determine when it will arrive. We do not ship kits without a tracking number to protect your personal information.

If you choose to use your own kit, you will choose the “own kit” option when choosing the shipping options, and upon receipt of your order you will be e-mailed a submittal form, a unique ID number that relates to your case (we cannot process any test without this), instructions on how to collect the samples, and our lab’s address to send your completed kit with samples for immediate processing.

If you have questions you can e-mail us at grandparents [at], or you may call one of our Case Managers at 1-888-391-5256 to discuss your case confidentially.