Nearly all DNA paternity test results can be reported accurately without the biological mother participating, but including her in the paternity test can strengthen the results in some instances. That’s why we strongly recommend that, whenever possible, the mother should be included in DNA testing.
How does including the mother help in paternity testing?
DNA paternity testing analyzes 15 Loci or markers (locations) on the DNA to determine if there are matches between the alleged father and the child at each location. If there are matches, each match receives a paternity index value which is used to calculate the combined paternity index and gives the probability of paternity (usually 99.99% when the alleged father is included as the biological father, or 0% if he is excluded).
Most paternity tests with only the alleged father and child participating do show conclusive results, meaning we have enough information to report conclusively or simply put, a yes or a no answer. There are occasions when the matches between the alleged father and child are inconclusive. This happens when the calculations involved could not get the probability of paternity above 99%, although there are matches. If this does happen, Identigene will ask for the biological mother’s sample to be included in the paternity test. If the mother is not willing or is unavailable, the results will remain inconclusive. Including the mother almost always gives conclusive results. We strongly recommend including the biological mother in any DNA test, including grandparent, avuncular, and sibling DNA testing.
Why Test the Mother?
Here is an example that we use to demonstrate how the mother’s profile helps strengthen paternity test results:
| Locus | Biological Mother (not tested) | Alleged Father | Child | Parentage Index |
| D2S1338 | — | 12, 13 | 10,12 | 1.845 |
| D2S1358 | — | 8,11 | 11, 14 | 2.714 |
| D8S1179 | — | 21.2, 32 | 19, 21.2 | 2.675 |
| D19S433 | — | 15, 18 | 12, 15 | 7.338 |
In this case, the probability of paternity is 98.2896% (the product of all the parentage indexes). The result is inconclusive because probability of paternity must be greater than 99% or at 0% to be conclusive, yet the alleged father and child match at all locations. Now, add the biological mother’s sample to the DNA paternity test:
| Locus | Biological Mother | Alleged Father | Child | Parentage Index |
| D2S1338 | 8, 10 | 12, 13 | 10, 12 | 3.489 |
| D2S1358 | 14, 17 | 8, 11 | 11, 14 | 5.114 |
| D8S1179 | 15, 19 | 21.2, 32 | 19, 21.2 | 3.619 |
| D19S433 | 8, 12 | 15, 18 | 12, 15 | 15.309 |
In the second table, the paternity index is increased and the probability of paternity increases to 99.9541%. Why? In the first example, one of the two markers from the child and alleged father match at each location. However, we don’t know which of the child’s markers comes from his mother and which must come from his father. By testing the child’s mother, we see which of the child’s markers must have come from the father.
Not only does the child match the alleged father, but the match is with the marker that must have come from the child’s true biological father (since we can see which marker came from the child’s mother). In fact, the index value is higher at each location because the biological mother participated in the DNA test.
If you have questions, don’t hesitate to call IDENTIGENE’s Client Support Team during business hours at 888-404-4363.
Brandi says
Hello. Back in 2011 a “peace of mind” test was supposedly performed between my daughter and her alleged father. He does not have any custody rights over her and performed the test without my consent with the obvious being that I was not there to provide a DNA sample. He provided me with a results letter concluding he was to be excluded as the alleged father. I however think this is a fake results letter. If I did not give a DNA sample and this was not a legal chain of custody test, then why are my name, DOB, race, and sample identifyer number listed, even though there are no allele numbers provided in the maternal section of the results. His and my daughter’s names, DOBs, races, and sample numbers were also listed on results letter. After research on your company website I discovered that “peace of mind” test results only give the sample identifier number and the role, (child, mother, alleged father) on the results letter, and a legal “chain of custody” results letter will state names and other identifying information on all parties involved. Dont I as the mother, have to be present for a legal test to be performed beings how my consent would be required? Did IDENTIGENE used to provide the names of people giving samples for their “peace of mind” testing or have they always followed the same protocol for information provided on test results. Do I have reason to believe I have been provided with a fraudulent results letter, considering the information provided? Any information would be appreciated. Thank you.
Identigene says
Hi, Brandi. Identigene used to put names on peace-of-mind tests, yes. Until late December, 2016. However, unless you provided a DNA sample (which you did not), then your name and information would not be on the results report. It may be a fraud not just on that level. He could have submitted someone else’s DNA and passed it off as his own, so take what he says and what he’s shown you with a grain of salt. If you want to know for sure, the court can compel him to do a legal, witnessed test. Something to think about!
kelly says
My adult twin sister and I want to do a Paternity to verify Paternity. Our parents are elderly and our alleged father is terminally ill. We are certain our mother would refuse to participate. The test is not for any legal purposes, and is strictly for our own information. Fist of all do my twin sister and I need to each submit our DNA? Secondly is absolutely necessary to have our mothers sample and if so could we send a toothbrush or other item?
Identigene says
Hi, Kelly. Chances are good that we would not need your mother’s DNA samples. But we do need a sample from your father, of course. If you are identical twins, then only one of you needs to submit samples. If you are fraternal, you may both want to test, but keep in mind there would be an additional lab fee. If your dad cannot submit a buccal swab, we can use a different type of sample, but there is a non-refundable $150 fee to test its viability prior to testing. I recommend you contact us directly to discuss your best options, or to order the test, at 800-344-9583. Hope this helps!
Kayla says
I think my DNA test is wrong! I only had one guy tested out of three and had it done through a different agency 6 years ago! I’ve been looking up DNA test examples lately because after watching some shows on tv I realized our test didn’t come back with a percentage only that he cannot be excluded as the father and in the chart they sent it’s all letters A,C,T. I’m to of getting him and one of the other possible father’s tested but would you need all three to get 99.99% accuracy?
Identigene says
Hi, Kayla. Unless any of the men share a close biological relationship (brother/father), then you only need to test one at a time. The one with the 99% probability of paternity is considered the father. So if the first man tested gets this result, you wouldn’t need to test the other two, because you can assume their results would show 0% probability.
Candice says
I am wondering if my test results seem like an example where the mother should be tested also. I slept with two different guys one month apart from each other but I was already pregnant before I met the second guy who is now convinced he is the father. Baby was born in the proper time for the first guy. Anyway the second guy got a court ordered test and someone it says he is the father. But I had not yet met him when I became pregnant. There are 11 areas between baby and alleged father where only one number is listed in the allele size and how can they know with so many shared numbers
HomeDNA Identigene says
Hi, Candice. When only one number is listed at a location, that means there are actually two of the same. So if “11” is listed, that really means “11,11.” One from the mother and one from the biological father. As for who’s the father, something must be off in the timing. Because there’s absolutely no way a man could get a court-ordered test that says he is the father if he isn’t. Including or not including the mother would not make a difference in this conclusion.