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Paternity Testing When Two Possible Fathers are Brothers or Related

Jul 30, 2018 | Paternity

Paternity testing when two possible fathers are related

It’s not unusual for a customer to tell us there are two possible fathers for a child and that those two fathers are biologically related. Although two possible fathers who are related don’t share all their DNA (unless they’re identical twins), they do share enough that getting conclusive results for paternity testing may be problematic. So can paternity-test results under these conditions be trusted? Yes! Here are some relationship possibilities and how they may affect test results.

If Possible Fathers are Brothers

It’s important to remember that, although they are closely related, full brothers each have very DNA profiles that are still quite distinct from each other. The chances of two brothers who are not identical twins matching a child at each genetic marker for paternity testing are not likely. But since the relationship between possible fathers is so close, we still recommend that each of the men test with the child, if possible. At the very least, it’s essential to notify the lab that there are two possible fathers and that they are brothers. The lab can then test more genetic markers, if necessary. It’s also important to include the child’s mother’s DNA in testing. When you include the mother’s DNA, it helps analysts to more easily determine which data is coming from the possible father and which is coming from her.

If Possible Fathers are Twins

Fraternal Twins

If the men are fraternal twins, the DNA connection between them is the same as it would be for “regular” brothers. As when “regular” brothers test, it’s best when both men can test and the mother should also contribute a DNA sample to strengthen paternity testing results (see If Possible Fathers are Brothers, above).

Identical Twins

For identical twins, their DNA is as you would expect: exactly the same! With today’s level of technology, this makes being able to genetically differentiate between the twins for paternity testing purposes practically impossible and completely cost-prohibitive since it would require testing most of their genetic markers instead of the standard 16.

If Possible Fathers are Father/Son

A full 50% of the son’s DNA comes from his father, so if these two men are the possible fathers for a child, there is a high possibility of obtaining a “false positive” result if only one of the men participates in testing. Therefore, the ideal is for both men to test with the child. If this isn’t possible for whatever reason, then the lab must be notified ahead of time (so that additional analysis can be conducted) and the mother should definitely send in her DNA sample as well.

If Possible Fathers are Cousins

Even men who are first cousins don’t share enough genetic material in common to cause a “false positive” for a paternity test: the connection is just too far removed to make a significant difference.

Final Thought

To repeat the most important points: In all cases where two possible fathers are closely related, it’s best if both men can test at the same time.  If there is a close genetic connection between possible fathers, and only one man can or is willing to test, it’s important to notify the lab about the biological relationship when submitting DNA samples: better safe than sorry!

Call us at 800-929-0847: We’re here to help.

Do you have a question about this topic? Ask in the comments and we’ll answer.

138 Comments

  1. Ruth Ann

    I have a son who is almost 30 there is a possibility between 2 men, not related one is deceased the other is alive & well. Which is the best way to get a DNA test on the man that’s still here. Only thing is he lives in a different state?? Help please? Can it be done by mail?

    Reply
    • DDC

      Hi, Ruth Ann. The possible father living in a different state is no problem. We would just send testing materials to you and your son at your address and then send a kit to the man at his address. Just give us a call at 800-681-7162 during business hours.

      Reply
      • Dave

        Hi I need your help, iv tested my Y dna with a Y dna genetic tester and tested the Y dna of the man I think is my farther, out of 132 genetics I shear 99.96% including 5 countries, I tested The YSNP numbers .cheers.

        Reply
        • DDC

          Hi, Dave. Your report should have provided a conclusion for you. If not, please contact the lab where you tested.

          Reply
    • Jolene

      This is going to sounds terrible but I slept with identical twin brothers and within 24 hours .. The situation is so complicated and doesn’t really matter to my question..
      but now I want to find out who the true father is of my son. He’s 10 months old. I have access to one twin for DNA . Would my sample help if I only tested one twin? Is it even completely possible to find the TRUE father if I were to get BOTH of them to take the test? Is my sample important to the data?

      Reply
      • DDC

        Hi, Jolene. Unfortunately, a paternity test won’t be able to determine which twin is the father, since the brothers’ DNA is virtually identical.

        Reply
      • Christine

        I have siblings but i have a unknown different father and i would like to see if my sibling fathers brother is my father

        Reply
        • Christine

          There is only access between myself and a sibling

          Reply
    • Rowan

      If the fathers are brothers can conclusive results be had if only one of the males is tested?

      -Prenatal blood/swab method.

      Reply
      • DDC

        Hi, Rowan. For prenatal testing, we cannot perform testing with two possible fathers who share a close biological relationship.

        Reply
    • Jamilynn

      My son and his first cousin could both be the possible dad of an 8mon old little girl only my son tested 99.99% the fater but being charged with sexual assault as to the 5 year age limit law between them well the cousin is a year older than he is but was wondering would that .01% of daught be a good fight to get things thrown out of court for his case

      Reply
      • DDC

        Hi, Jamilynn. Your son and his cousin don’t share enough DNA to provide a “false positive” for your son’s test.

        Reply
      • Laurie

        It’s possible my first cousin is my half sibling. My father & his mother are blood bro & sis but now his father is possibly mine …. both fathers are deceased. How can we test to know if his father is also my father?

        Reply
  2. Sami

    My daughter had a dna test done and the results came back 99.96 but the other alleged father who is the other mans brother was not tested nor mentioned to the testing agency is there any possible way that the results could be wrong and his brother is in fact the child father?

    Reply
    • DDC

      Hi, Sami. In cases like this, a false positive may occur. It really depends on how much DNA the brothers happen to have in common at the locations tested. It’s essential that your daughter be tested again, hopefully this time with both men. If that’s not possible, then the lab definitely needs to be made aware of the other alleged father and his biological relationship to the man being tested BEFORE they do the testing.

      Reply
  3. Julia

    Two men get tested to determine the paternity of their daughter (they both think they are the father).
    After the tests, one of them is the father. Neither one of the men suspects they are related to each other. Let’s presume they are.
    Would the DNA test done to determine paternity inadvertently discover the relationship?

    Reply
    • DDC

      Hi, Julia. That’s an excellent question! It depends on how much DNA the two men share in common, whether they’re brothers or father/son, etc. What I’ve definitely seen a few times is this: a man is excluded as the father (meaning he’s not considered the biological father), but the lab made a notation in the report of the possibility that the actual biological father is related to the man who was tested.

      Reply
    • Laurie

      I’m 51 now and finding out that my fathers brother in law may actually be my father. Both are deceased, would I check both my aunt (fathers sister) & her son or how would that work? If I don’t have dna matching my aunt but I match her son does that mean that my uncle(fathers bro in law) is my actual father?

      Reply
      • DDC

        Hi, Laurie. You most likely would do an avuncular (aunt/uncle) test. Since your situation is complicated, I suggest you contact us directly for a free confidential consultation to determine what type of testing might be best: 800-681-7162 (M-F, 8 AM to 8 PM Eastern).

        Reply
        • Rebecca

          My full sister had an affair with my ex husband, and during that time she had a baby, my niece. She lost custody of my niece due to drugs, and I have the baby in my custody now. Neither one of the adults are willing to participate in a DNA test to determine paternity. Can I have my niece tested against my children to determine paternity?

          Reply
          • DDC

            Hi, Rebecca. Yes, you can do a sibling vs. half-sibling test to help determine the relationship between the niece and your own kids, as long as you have legal guardianship. I suggest you contact us at 800-681-7162 (M-F, 8 AM to 8 PM) for a free consultation with one of our experts.

        • Stephany

          I have a question I had relationship with a father and son not knowing anything of the situation of them being related but I had the jr test my courts and I advised the courts of the situation! The son came back 99.99 percent the father is the test accurate? I was told maybe not because a father and son share dna but the courts knew before testing about father and son in question

          Reply
          • DDC

            Hi, Stephany. Since the court was notified, they should have also advised the laboratory and the lab would have taken this information into account when performing their analysis.

      • Laurie

        What if the aunt passes away before she agrees to a test?

        Reply
  4. DANI

    Hi, Both fathers in question are dead but my sisters father is the brother of the man I think is my dad. He is also dead.. Can I do a DNA TEST with my sister to see if our fathers are related.. We both have the same Mother.

    Reply
    • DDC

      Hi, Dani. Because you and your sister share the same mother, you already know you are half siblings and a test is not necessary to determine that. You may want to test with someone whom you are certain is related to your possible father in the first degree: like a known child of his. I suggest you give our experts a call so you can walk through your situation with them on a one-on-one basis and see what your options are: 800-681-7162.

      Reply
      • marlene

        hi….what if two guys are involved and they are related but only one does the test and the percentage came back as 97% is he the biological father

        Reply
        • DDC

          Hi, Marlene. If the lab was not notified ahead of time that the other possible father is a close relation (brother/father/child) of the man being tested, than that information was not able to be taken into account during analysis and any inclusion result cannot be relied upon to be accurate.

          Reply
      • Erin

        Hello! I have a unique to situation. I have used your site for dna however. Have now found out more information. It is an incest case. Originally we tested my bio dad myself and the child out of invest. We were told it was my dad and his sister at a young age then had a child. We tested incest child,and my dad. However the test was not 99.9 I didn’t know we could go further as now thier is speculation that it was may have been my dad & his sisters actual father. My grandpa! Not my dad at all? My dad has since passed since first test and unfortunately my dad’s family will not allow a swab of “grandpa” . Is thier anyway to retest my “half sister(thru incest) and myself with proper testing to see if we really do have same father now knowing more information?

        Reply
        • DDC

          Hi, Erin. You’ll need to call us directly to see what your best options are in light of this new information: 800-681-7162 (M-F, 8 AM to 8 PM Eastern).

          Reply
      • Earnest

        I had a dna test done and I was turned out to be 99.8 Percent the father , but she had relationship with my brother and he wasn’t tested do we need to do another to see if I’m the actual father or if he is .. we are full siblings .

        Reply
        • DDC

          Hi, Earnest. Unless the lab was told ahead of time that the other possible father is your brother, then yes…another test would be advisable. This time, it’s important to either have your brother test too or at least let the lab know of the relationship so that they can take this info into account when performing their calculations. If the mother is willing to test too, that’s optimal. Good luck! If you are interested in testing through DDC, contact us for a free consultation at 800-929-0847 (M-F 8 AM to 8 PM Eastern).

          Reply
    • Anne-marie

      Me and my dad got a DNA test but there is a possibility that his brother might b my dad. The test come back saying he isn’t my dad but is there anyway we can determine if we are at least related in someway from the test result

      Reply
      • DDC

        Hi, Anne-marie. The best way to answer that question definitively is to test the uncle, if possible.

        Reply
        • Marie

          My son and alleged father had a DNA testing done. Results came back he cannot be excluded as the biological father and it was 99.9987%. The alleged father believes he still is not the father since the other person did not test. There is no relation other than same ethnicity. Is another testing needed?

          Reply
          • DDC

            Hi, Marie. Unless the two men share a close biological relationship, then no, there’s no need for additional testing. 99.9987% is an extremely conclusive result.

  5. John

    Hi, what if the two potential fathers are half brothers ( they share the same mother but different dads), is it possible to accurately determine the father of the child if you only have samples from one of the half brothers?

    Reply
    • DDC

      Hi, John. The answer is yes. However, two things are very important:
      (1) The mother of the child should be tested also
      (2) The lab must be notified ahead of time that another alleged father is the half-brother of the man being tested. This way, they can take this fact into account when doing their analysis.
      Hope this helps!

      Reply
    • jenny

      Hi, how will i know if its my husband child can they used his brother sample as her kid and my husband sample to make a positive result? My husband is forcing to be the father but we don’t see any similarities of him and the child and the girl confessed that they were five men at same time when they mess up together.

      Reply
      • DDC

        Hi, Jenny. Substituting the uncle’s DNA for the possible father’s is not likely to yield a positive result. To be safe, it would be wise to insist on a legal paternity test where DNA collection is witnessed and IDs are checked. I suggest you contact us directly to speak with an expert at 800-681-7162 (M-F, 8 am to 8 pm Eastern).

        Reply
  6. Bob

    I am interested in clearing up the relationship between myself and sibling. I have a suspicion that my father and my siblings father were brothers (same mother) We are older and parents all deceased. Can this be definitively shown?
    Thank You

    Reply
    • DDC

      Hi, Bob. Did either of you know your fathers?

      Reply
      • Steve

        Like Bob (Nov. 15 2018 above) my brother and I share the same mother. She is still living. The three of us have been DNA tested: mom and I via 23andme, and my brother by MyHeritage. We’re confused in that my brother and I only share (as per MyHeritage) 38.4% DNA. I thought we would share closer to 50%. Since our shared DNA percentage is much lower, could this mean we might have separate fathers, who were perhaps brothers? Or is this 38.4% in the realm of same parents?

        Reply
        • DDC

          Hi, Steve. I talked to our Chief Science Officer personally about your question. He thinks that 38.4% if a little low, but it’s not out of the realm of possibility for two full brothers. It really just depends on what you inherited from both parents in the genetic lottery. It is possible that you had fathers who were brothers…have you asked your mother about this? If it is possible that the fathers were brothers, then doing a Y-STR test with you and your brother wouldn’t do any good, since the two fathers would also share the same Y chromosome. You could do a sibling vs. half-sibling DNA test (with your mother including her DNA) while notifying the lab ahead of time that there may be another alleged father who is the brother of your presumed father.

          Reply
          • Steve

            Thank you! Great information and so quickly. Will connect with my brother and maybe mother as well, however this could be a touchy topic. She would probably be up for another DNA test and I could just leave it at that. My brother and I are quite interested in finding out more. Again – thank you!

          • DDC

            Yes it might be a touchy topic, for sure. You’re welcome, and good luck. If you have any other questions, feel free to reach out again.

        • Deborah

          I had sex with two different men at the same day who could be the father now?note:they are not related at all,

          Reply
          • DDC

            Hi, Deborah. Only a DNA test would be able to give you that answer.

  7. Steven

    Hi, I have a couple of questions I thought hopefully you might be able to answer…1st if a DNA test came back only 97% probability, would that mean I’m the Father? And second my kids Mom & my mom are sisters, my mom had here tubes tied before I would have been born. But just by some miraculous chance my mom did conceive me after that, which would obviously make my kids mother myself maternal cousins, what kind of result would you get?

    Reply
    • DDC

      Hi, Steven. I want to make sure I understand this correctly. Your kids’ mom is your maternal aunt?

      Reply
  8. Steven

    What blood types aren’t compatible without having the rh- shot?

    Reply
  9. Scott

    I have a question which I have gotten some conflicting answers on. The question I have is if my fathers brother (my uncle) is the other possible father of my child, is that a close enough relative to me to produce a false positive for me on the paternity test ? I already tested and got back the result of 99.99% with a CPI of 19,091. I am wanting to know if we are close enough relatives for it to affect the results of my test ? I would really appreciate your help on sorting this out. Thank you.

    Reply
  10. Anna

    I am not sure if the father or son is my child’s father. Will the paternity test be clear if only the father is willing to be tested and the son is actually the father?

    Reply
    • DDC

      Hi, Anna. Excellent question! This is very important: If only one of them can or is willing to test, you MUST let the lab know ahead of time that there is another possible father and what their biological relationship is. That way, the lab can take this into account in their analysis and test more genetic markers, if necessary, to obtain conclusive results. It’s also helpful for you to contribute your DNA to the test as well.

      Reply
      • Ann

        What will the DNA results show if I decide to just wait and get results with father being tested for paternity as the son has refused? Will the test results be negative or inconclusive if he is not the father?
        I have a suspicion that the son is actually my child’s father but I can proceed further if the results are not conclusive.

        Reply
        • DDC

          Ann, with today’s technology and methods, an accredited lab should never return an inconclusive result for a paternity test. When the father tests, it’s absolutely essential that you let the lab now ahead of time that the other alleged father is the son of the man being tested. That way, the scientists can take that info into account when doing their analysis. They can test additional markers, for example.

          Reply
        • Jenn

          I’m curious ann as to what the results showed, I’m in the same situation and could use some answers.

          Reply
  11. Juliet

    Hello! I been having this gut feeling ever since my ex took the DNA test about 3 years ago that he is the father, but when he did the test, the results came negative, and he was very upset, there is another guy who I am having a problem contacting him to also get the paternity DNA test, I even got him into child support JUST for him to do the Test! what are the chances if my ex takes a second DNA blood test but this time would be him, my son(9) and me? I mean how different the tests are compared to the swab, and only taken by the alleged father and child? And also having the same birth marks can prove the alleged father is the one? (meaning my ex) even though he already took the test and it came negative?
    Thanks!

    Reply
    • DDC

      Hi, Juliet. DNA collected via blood and via swab is exactly the same…one method is not more “accurate” than the other, in terms of results. If DNA for the same exact people who did the first test is submitted again for the second test, you can expect to see the exact same results, especially if you used an accredited and reputable lab like ours. A birth mark alone is not proof of biological relationship. All this being said, if you still have doubts, why not do another paternity test with your ex? I recommend doing a legal, witnessed test so that results can be used for court, if necessary.

      Reply
  12. Mo

    Hi,
    My husband was tested 21 years ago for a child with his ex. She(the ex ) also slept with his brother. Now the conclusion on the results said that my husband “can not be ruled out as” . what does that mean ? His brother has not been tested.

    Reply
    • DDC

      Hi, Mo. For the technology at the time, this was probably as conclusive a result as the lab was able to give. It means just that…your husband might be the father, or he might not. The lab could not say for sure that he’s not the father. Has he considered testing again, now that the technology is so much more improved? If he does, it’s essential that he tell the lab ahead of time that the other possible father is his biological brother. That way, the lab can take that information into account and perform additional testing, if necessary, to obtain a conclusive result.

      Reply
  13. Erik

    This is off my results papers,
    Conclusions of DNA Paternity Test
    Based on the genetic testing results obtained by PCR analysis of STR loci, the probability of paternity is 0.099% as compared to an
    untested, unrelated random man of the Caucasian population (prior probability = 0.5). Please note that 2 mismatches (at loci D21S11
    and D5S818) have been found in the comparison of the profiles between the alleged father and the child. Possible relationship
    scenarios are as follows:
    1. The Alleged father is not the biological father of the child or may be a possible relative of the biological father.
    2. The Alleged father is the biological father of the child but there is a double mutation in the Child.
    My questions are, if I have a 0.099% chance of being the biological father, why is it saying that I may be a possible relative? Just because of the other loci are matching? Is it fairly common for random people to have a lot of strings match? What are the odds/chance that a double mutation can occur?

    Reply
    • DDC

      Hi, Erik. Double mutations are not that unusual. I’m surprised the lab you used didn’t just take a little extra time to test additional genetic markers or include the mother in testing. Yes, because there are matches at all the other loci, that’s why they gave you the possibility of being a close relation (brother to the actual biological father, for example), although the chances of that are relatively small. Sounds like you need to contact the lab and ask questions about why they weren’t able to give you a more definitive conclusion.

      Reply
    • Tracey

      If I have had a 99.99999 positive test but then find out that my Mum and Uncle had an affair, could my uncle be my father? When I sent my results back, I didn’t know this information so didn’t inform the lab that there may be another brother involved!

      Reply
      • DDC

        Hi, Tracey. You may want to perform another test, yes.

        Reply
        • Erik

          Me and an alleged father did a DNA paternity test few years ago and it came back negative. We do share DNA in 8 locations out of 15 (+ X,Y), in these locations:
          D3S1358,
          D2S1338,
          D16S539,
          D10S1248,
          D2S441,
          vWA,
          D8S1179,
          FGA.
          Here are locations that we don’t share:
          D19S433,
          D22S1045,
          D18S51,
          D1S1656,
          TH01,
          D21S11,
          D12S391.
          I’m wondering if we are related and how closely.
          I also did DNA testing with MyHeritage and one man shares 6,2% DNA with me that would make him my (paternal) great uncle or 1st cousin once removed or 2nd cousin. I contacted his sister (also through MyHeritage) and I’m pretty sure I figured out who could be my father by their family history/tree. I want to contact him but I’m terrified because he has no idea that he could be my biological father. My mother and alleged father were positive that they were my biological parents. I should ask this newly found alleged father to make paternity test but I don’t know how to approach him since he has his own family and quite high status job.

          Reply
          • DDC

            Hi, Erik. I cannot speak to results from ancestry companies, sorry. As for the paternity test you did, barring genetic mutations, you must match at every genetic locus tested in order for him to be considered your biological father. The fact that you share DNA in 8 locations means little and is not proof of a different type of biological relationship, like uncle or cousin. As humans, we all share a great deal of the same DNA: You and I probably match in many places. I wish you well with your search!

        • Eve

          How probable is it, that both brother would match at all 20 locations in a test with a child? I mean in average.

          Reply
          • DDC

            It is unlikely, but possible. I cannot provide an average for you.

  14. Vin

    Hello! i just want to know if its necessary to get additional paternity test when i get a conclusive result? ex. if i get additional 3 or more test is there a chance that the result came different from one another?

    Reply
    • DDC

      Hi, Vin. The results should be exactly the same for each test as long as the same DNA is submitted and the same ethnicity is stated. If you already got a conclusive result, you don’t need to do another anyway.

      Reply
  15. Grace

    Hello! Is it possible to get a conclusive result in paternity test if one of the participant have a mutation(s)?

    Reply
    • DDC

      Hello, Grace. Analysts take mutations into account when doing their calculations plus they test additional DNA markers in order to obtain conclusive results.

      Reply
  16. Roger

    I want to know if dental fillings/pasta on teeths can affect the paternity results in any way? As far as i know fillings contains many chemical.

    Reply
    • DDC

      Hi, Roger. No, that’s not a problem and won’t affect results.

      Reply
  17. Adm

    If there is tow brothers (from the seam father and seam mother) and a Child. And we have test Only one of the brothers and the Child can be confirm this brother he is the father or not with out testing the other brother?

    Reply
    • DDC

      Hi. As stated in the article you’ve commented on, it’s best if both brothers can test, along with the child’s mother. If that’s not possible, it’s absolutely essential to let the lab know ahead of time about the other possible father and his relation to the man being tested. That way, the lab can take that knowledge into account when doing its analysis and extra DNA markers can be tested if necessary for conclusive results.

      Reply
  18. Sherry

    My boyfriend recently had a court ordered DNA test through DDC. The results came back as 99.9%. We also recently found out that the mother of the child may have (both parties deny this, but we’re suspicious) slept with his full brother around the same time of conception. Is it possible that the results were wrong? Also, is it possible to re-test the specimens?

    Reply
    • DDC

      Hi, Sherry. Brothers share 50% of their DNA only, so it’s unlikely that there was a “false positive” result. Yes, if indeed his test was done through DDC, since he did a legal test we can re-analyze the data, but keep in mind there is a fee for this service. Your boyfriend should call us at 800-681-7162 (M-F, 8 am to 5:30 pm Eastern).

      Reply
  19. Sherry

    How much is the fee?

    Reply
    • DDC

      Hi, Sherry. A new legal test is $300-500, depending on where you live and other factors.

      Reply
  20. Jeana

    My sister and I have the same mother(she has passed) but our father might not be mine. It is possible his brother is. Is there a way to find out if my sister and I have the same father without involving either or the brothers(our dad and uncle). I want to know but do not want them to know. And my sister is willing to get tested with me.

    Reply
    • DDC

      Hi, Jeana. What you are seeking is a full vs. half-sibling test. It’s unfortunate that your mother has passed, since her participation would have greatly optimized your chances of getting conclusive results. You and your sister can do a test, but it’s absolutely essential to let the lab know ahead of time that the possible fathers are brothers. This way the lab can take this information into account when doing their analysis and test additional markers, if necessary. Adding other relatives like your mother’s sister would be helpful too, but without your mother being available, you might get conclusive results but then again you might not. It just depends on your shared genetic data.

      Reply
  21. Christy

    My moms sister and my dads brother had a child. I don’t believe my son is mine, I believe he may be my cousins. He will not take a test. So I’m asking if myself and my son took the test, would this be accurate? Could it be possible that our DNA is that similiar? Or No?

    Reply
    • DDC

      Hi, Christy. I’m confused by your name. Are you the mother of the child or the alleged father of the child?

      Reply
    • Terri

      I sent in child’s sample and 2 possible fathers samples in one envelope. The results have been posted and 1 shows as the father @ 99.999 but I was not given the name I provided on the envelope. Only a number for the sample. How do I determine which person is my father?

      Reply
      • DDC

        Hi, Terri. If your test was with DDC, give us a call at 800-831-1906 (M-F, 8:30 am to 5:30 pm Eastern).

        Reply
  22. Danny

    Adding to my question above..
    Since I did a legal Non-Invasive prenatal test can DDC take another look at my results and see to make sure I couldn’t be a distant relative to the child? I am the only one who can be tested. or do we have to re-test..

    Reply
  23. James

    If alleged fathers are father and son. And one of them had a negative test result with the baby. Is it 100% that he is not the father for the child?

    Reply
    • DDC

      Hi, James. Yes, it is.

      Reply
  24. Lou

    Hi if the alleged father is tested and he is a first cousin to the mother and the results say he is 99.99999999%, is this accurate? Will the mother and tested fathers relationship as 1st cousins affect the DNA results if the lab are unaware of this relationship?
    Thanks,
    Lou

    Reply
    • DDC

      No, a first-cousin relationship is not to worry about since they only share about 12.5% of the same variable DNA. We’re more concerned with a father/son, nephew/uncle, grandson/grandparent relationship. As stated in the article you commented on: “Even men who are first cousins don’t share enough genetic material in common to cause a “false positive” for a paternity test: the connection is just too far removed to make a significant difference.”

      Reply
  25. Ronald

    My ex wife told friends that my father is my son’s father not me, my has passed away and she refuses to be apart of any genetic testing, can i have both of my sons dna tested along with mine to find out?

    Reply
    • DDC

      Hi, Ronald. Yes, you can. Just be sure you specify your sons’ possible relationship with your dad when ordering the test. That way, we can keep that information front and center during the analysis and then test additional markers, if necessary. Call us for a confidential, no-obligation consultation at 800-681-7162 (M-F, 8 am to 8 pm Eastern).

      Reply
  26. Lashawn

    My son and the alleged father was tested and the results came back “0” but I was never tested. Should I reconsider retaking the test so I can be tested as well. They have the same numbers on some of the markers

    Reply
    • DDC

      Hi, Lashawn. Unless the lab requests it, your participation is not necessary. Because we’re human and we share a lot of the same DNA, it is not unusual for people to have some of the same data at different genetic markers. You and I probably do too! What’s most important in paternity testing is for there to be matches at all genetic markers. Sometimes there may be one or two mismatches due to genetic mutations, but those are taken into account during analysis.

      Reply
  27. Tina

    My mother had 2 possible fathers. Both of whom are deceased. My mother does not want to know who her bio father was. However due to medical history, I feel its important for me and my children to know who my grandfather is.

    Can I take a dna test with one of her possible paternal siblings to find out if he is my uncle? They do not share the same mother

    Reply
    • DDC

      Hi, Tina. Yes, you can do an avuncular (aunt/uncle) test, but keep in mind that the chances of obtaining conclusive results would be much greater if your mother participated. This is further complicated by their being half and not full siblings. I suggest you contact our experts directly at 800-681-7162 (M-F, 8 am to 8 pm Eastern).

      Reply
  28. Anonymous

    My ex took a test it came back less the 100% his brother is now taking a test would the rest of that percentage likely be the brothers

    I’m then mum so I know I make up for a part of it but I’m very confused one is older then the other I’m hoping that I can get the answers

    Reply
    • DDC

      Hi, Anonymous. A probability of paternity for paternity test can never be 100% since DNA testing is based on statistics. So without also testing every other man in the world with the same racial background as your ex, the highest probability of paternity is 99.9%+. If the test show a probability of relationship of 99% or higher, then your sons are considered your ex’s biological sons.

      Reply
      • Anonymous

        In this scenario the father could be a son or his dad.
        There is a lady who we have always considered my half aunt (my grandfather’s daughter) but there was a chance she was my father’s daughter as well making her possibly my sister. My grandfather (when my dad was a teenager my dad’s father) had an affair with my dad’s girlfriend and she became pregnant with said lady. Both my grandfather and my father have passed now. How/who would we get tested to get the most accurate results?

        Reply
        • DDC

          Hi! You didn’t mention whether or not the lady is willing to do DNA testing. If she’s not, then the issue is moot. If she does agree to testing, I suggest you contact our experts directly to determine how to best proceed. That number is 800-681-7162 (M-F, 8 am to 8 pm Eastern).

          Reply
  29. Catherine

    Hi, me and my dad where tested, with the 20 loci test. The result was 99.99999998% (matching on all locis) and the combined index was 6,582,606,282. My unce, who deceased, could theoretically also be the father.
    In your article it says “The chances of two brothers who are not identical twins matching a child at each genetic marker for paternity testing are not likely. ”
    With the numbers above given, could you give me an estimation of how probable it is, that my uncle could have been the father? It should be almoust impossible, right?
    Thank you

    Reply
    • DDC

      Almost impossible, yes.

      Reply
      • Catherine

        Thank you very much!
        Would it be possible to guess any percentage range? For ecample: Is the possibility less than 1% or more like less than 0,00001%

        Reply
        • DDC

          Without all the data, I cannot provide a percentage range, no. Sorry!

          Reply
  30. Rayven

    Hi, I have a daughter and she has 2 possible fathers, they are brothers as well. I had her july 8th and the conception date was October 16th and I slept with them both within the week though. I have to get a paternity test on the 22nd. I need to know. What will happen if the one that is getting tested isn´t her father and how much of a possibility is it for them both to have very close DNA..

    Reply
    • DDC

      Hi, Rayven. Regardless of conception date or who you think the father might be, it’s ABSOLUTELY ESSENTIAL to let the lab know ahead of time that the other possible father is the brother of the man being tested. That way, they can take that information into account when performing the analysis and test additional genetic markers, if necessary. You should also contribute your DNA. Ideally, both men should be tested.

      Reply
  31. G

    My brother and I got tested to try and find out if my dad was actually my uncle or not, the results came back 99.78%
    Is that 0.12% anything I should worry about?

    Reply
    • DDC

      Hi, G. Did you do an avuncular test or a paternity test? Your statement isn’t clear. I suggest you contact the lab where you tested to have your questions answered.

      Reply
  32. Elizabeth

    I tested potential father number one ( brothers ) and told them and got a negative then yrs later had to test potential father number 2 and got a 99.97 but says it found a mutation and doesn’t exclude close relatives ie brother or father .. is it possible that potential father number one could b . Mother was not tested either time .

    Reply
    • DDC

      Hi, Elizabeth. If potential father #1 was excluded in a separate test, then that is conclusive for him (assuming he submitted his own DNA for testing). Potential father #2 is considered the biological father with a 99.97% probability of paternity, and since you already know it cannot be potential father #1 (assuming he submitted his own DNA for testing), then you can conclude the result for father #2 is correct. All that being said, unless you know for certain that father #1 submitted his own DNA for testing, you may want to test him again. This time include the mother’s DNA and inform the lab that the man being tested is the brother of the other man so that this information can be included in their analysis.

      Reply
  33. Puleng

    Will I get the correct results if both possible Fathers are related to the mother ( possible fathers are a father and a son and the mother is the daughter to the same father and mother as the son)

    Reply
    • DDC

      Hi, Puleng. All those complicated relationships will need to be explained to the lab prior to testing, and then a decision can be made whether or not testing is possible.

      Reply
  34. ADAM

    Hello, is the test reliable if used sample from grandmother (father’s mother) , and her grandson ?

    Reply
  35. Julie

    I have adopted two girls, both of which have the same birth mother. We have been told who the father is of one, or at least who she believes is the father but there were multiple possibilities of the other. Is there a way to just run the DNA profiles of my two girls to see if they have the same father? Or would we have to have the men involved?

    Reply
    • DDC

      Hi, Julie. You can do a full-sibling vs. half-sibling test. Ideally, the birth mother would contribute her DNA as well to optimize conclusiveness of results, but since yours is an adoption case, that may not be possible. Contact us for a free consultation at 800-681-7162 (M-F, 8 AM to 8 PM Eastern).

      Reply
  36. Matthew

    Hi, i have results from paternity test between father,mother,son and daughter. It’s possible that both baby’s have same alleles at 9 loci from 24 tested? Can by my half brother (same father) father ?

    Reply
    • DDC

      Hi, Matthew. Without seeing all the data, I cannot confidently provide an answer. Sorry! I suggest you contact the lab where you tested since they have access to all the data and ask questions.

      Reply
      • Matthew

        I can send report with loci and alleles to you. It’s possibility that the lab maybe manipulated something. Can you recognize false positive results?

        Reply
  37. Thomas

    I was tested for paternity but was never shown results. I suspect a close relative to be the father. But The mother says the results were that I am the father. Could she have been given a 50% or 75% percentage because the father is my relative. Or would It just state Postive or negative for paternity?

    Reply
    • DDC

      Hi, Thomas. It would just state whether it’s an inclusion or an exclusion for paternity.

      Reply
  38. John

    Hi, I was wondering if you guys could do a paternity test on a baby who’s still in the womb to determine who’s the father between 2 brothers? The baby is about 4 months along.

    Reply
    • DDC

      Hi, John. Both brothers would need to participate in the same test. If that’s not possible, then testing would need to wait till after the baby’s born.

      Reply
  39. Cathy

    Hi, is there a test to determine if I am the 1st cousin with a Whopping 1479Cm match, or am I a half sister to a man who is possibly my uncles child. This man is so close to to me , our DNA is like 3/4 sibling.

    Reply
    • DDC

      Hi, Cathy. Please contact us directly at 800-681-7162 (M-F, 8 AM to 8 PM Eastern) to speak with one of our experts and determine testing options.

      Reply
  40. Samantha

    My dna test came back as 97.99% with the man that was tested. He has a brother who might be my father as well. That man was not tested. Does that 97.99% mean there is a change his brother is my father and not him?? Since it was not at 99.99% result

    Reply
    • DDC

      Hi, Samantha. Was the lab notified ahead of time that the other possible father is the brother of the man tested? If not, then new testing is needed.

      Reply
  41. Pamela

    So I have two nieces and my sister slept with two brothers and their father meaning the two girls grandfather. The girls have been curious to know if they share the same father and got a DNA match. Does this mean that only one of the brothers is the father or is it possible that the DNA is shared between the two brothers or a father and either one of them could be the paternal father?This all happened a few years apart so nobody really knew at the time what the real situation was. The girls just do a DNA test and they’re assuming the one brother is their dad. Is it possible the grandfather for the brother that she slept with before they were born to be a DNA match to one of them

    Reply
    • DDC

      Hi, Pamela. Did they do ancestry testing? What do you mean by they “got a DNA match?”

      Reply
  42. dnaisnotjustformaury

    Paternity test q.. 2 brothers from one mother
    The mother was married to father #1 and she had sons hereafter called son1 and son2

    There are 2 possible fathers for son #2 which could be father #1or father #2.. and they were brothers

    Both possible fathers are now deceased and the only other living sibling is their sister

    Now there are no known available dna samples for father 1or 2since both have been deceased for years. Also of the son1 and son2 they do NOT get along so obtaining a dna sample of brother 1 in theory is possible butpote totally problematic

    DNA from son2 the mother and the fathers living sister are easily enough to obtain

    Now the easiest way I thi k to determine son2s fatherwould be comparison of dna with son1 whom is known to be father1s kid.
    Besides that obvious comparitive is there another potential way given this available dna info to determine if son2 is the son of father1or his brother father 2

    Reply
    • DDC

      You’re right that the best way to determine son2’s father would be to test him with son1. Since that seems unlikely given that they don’t get along, I suggest you contact us directly to speak to one of our experts and see if there is another viable option: 800-681-7162 (M-F, 8 AM to 8 PM Eastern).

      Reply
  43. Stella

    Hello, I have a 3-year-old girl and am in a confusing situation. so my daughter has dimples on both cheeks, but neither I nor my husband has dimples in our families both mum or dad’s side. My husband is also a second cousin from my mum’s side. there is another man who has dimples in his family who could be the possible father of my child. I had a paternity test taken with Me Baby and my husband and the result was positive 99.99% for the father but am not sure if this result is positive cause my husband is my second cousin. I really doubt this cause was told by a friend dimples occur only in families hence I feel this other man could be the father. Is there any test that can prove this??

    Reply
    • DDC

      Hi, Stella. Unless the untested man is a close biological relation to your husband, then there is no need to test. Dimples are a genetic mutation; it may be that the trait is in one of your families way, way back, or your daughter has her own mutation. It’s not scientifically sound to use this trait, or lack of the trait, as a determinant of a biological relationship. DNA is the only sure way to determine paternity.

      Reply
  44. Mesue

    For the last 43 years &7 months. I thought one man was the father of my son. I put him up for adoption when he was born. A year ago he found me. What I thought was his father all his life had died. I kept in C touch with his fathers brothers as we all grew up in the same little town. Since then I took a DNA test that proves I’m his biological mother at 49.9 % and I his father is 51.1%. What I thought for all this time as being his biological brother and cousin, they said they took the test an they said they were not a match. Since this happened my son has kept searching for his biological father. I told him I’d help him in anyway. My son said he found a lady in Oregon that is 12% his relation. What part of the connection would she be? Could I have the brother of the man that I thought was his father take a DNA test would it b prove he was his Uncle?

    Reply
    • DDC

      Hi, Mesue. A 12% connection with the lady in Oregon sounds like a cousin. Yes, your son could do an avuncular test with the brother of the alleged father. You should contribute your DNA as well. I suggest you contact us for a free confidential consultation at 800-929-0847 (M-F, 8 AM to 8 PM Eastern).

      Reply

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