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How Can My Paternity Test Samples Get Messed Up?

Nov 18, 2019 | Paternity

How Can Paternity Test Samples Get Contaminated?

 “Uh oh. I think I messed up my paternity test.”

Our customer-service specialists often hear this statement from clients who call in, worried about whether or not the samples they submitted for their at-home paternity test or other relationship analysis might have been contaminated.

When you order a test, you and the lab form a partnership in the proper handling of these samples.  As a highly-accredited laboratory, we take our responsibility seriously and have strict processes in place to ensure samples are not contaminated at the lab level.  As a participant in the test, your job is to get your samples to the lab in the best condition possible.

Collecting DNA with cheek swabs is easy and painless, but do it with care.

DNA collected via cheek swabs is every bit as effective for testing as a blood sample. The process involves vigorously rubbing the inside of the cheek for 30-60 seconds for each swab included in the kit to ensure enough cells are collected for testing. So how might samples for a paternity test get contaminated?

1. Eating, Drinking, or Smoking before Swabbing

All participants in a paternity test should refrain from eating, drinking, or smoking for one hour prior to swabbing—this is also true for nursing infants. Although having foreign residue in your mouth won’t change your DNA, it can definitely affect the quality of the samples by degrading them, making it difficult or impossible for robots at the lab to extract usable DNA from the swabs.

GOOD NEWS: This type of contamination doesn’t affect the results of your paternity test because the lab simply stops testing and asks for new samples before proceeding with analysis. New testing materials are sent to you at no charge.
BAD NEWS: It’s a source of stress for you because your results will be postponed and you have to wait a little longer.
PREVENTION TIPS: If one of the participants eats, drinks, or smokes prior to swabbing, just delay swabbing for an hour.

2. Cross-Contamination during DNA Collection

To maintain the swabs’ integrity, do your best to avoid the following:

  • Handling the soft ends of the swabs
  • Dropping swabs
  • Allowing the heads of swabs from two different people come into contact with each other
  • Putting swabs from two different people in the same envelope

GOOD NEWS: If contamination occurs as a result of any of these actions, the lab will catch it and ask for new samples.
BAD NEWS: Again, you have to wait longer for results if the lab asks for DNA recollection.
PREVENTION TIPS: Handle swabs with care and follow all kit directions.

3. Mailing Wet Envelopes or Re-Using Plastic Packaging

Wet Envelopes

It’s not at all unusual for a little excess saliva to get mixed in with cheek cells when collecting DNA for a paternity test. As a result, the sample and even the mailing envelopes may become a little wet. If mailed while damp, packaging could tear and swabs can become contaminated.

GOOD NEWS: DNA samples can simply be collected again.
BAD NEWS: There is a delay in issuing results.
PREVENTION TIPS:

  • The swabs for a paternity test are designed to collect cheek cells—not saliva. Be sure to only swab the insides of your cheeks and avoid gum areas
  • If a swab is “too wet,” hold the swab up and wave it in the air for 60 seconds to dry it a bit before placing in the paper sample envelope
  • If an envelope still gets a little wet, lay it on a clean counter and allow it to air-dry prior to mailing

Re-using Plastic Packaging

DNA is organic material and is therefore susceptible to becoming moldy under adverse conditions. Mold degrades DNA on a swab extremely fast, and this kind of contamination makes using the sample for testing impossible. If you put swabs containing DNA back into the plastic packaging the swabs came in, the sample can’t “breathe” and the consequence is almost always rapid mold growth—even if you mail samples off right away.

GOOD NEWS: New DNA samples can be collected.
BAD NEWS: You have to wait longer for results.
PREVENTION TIPS: Once you’ve collected the DNA, make sure the swabs have been air-dried as much as possible and then place them in the paper envelopes provided in your kit.

 Final Thoughts about Swab Contamination

It’s important to remember that swab contamination can never “change” the results of a paternity test or “change the DNA.” So there’s no need to worry! If contamination occurs, the lab always catches it, and the worst that can happen is the lab will ask for samples to be collected again. Just be sure to carefully follow all instructions that come with your paternity test, and feel free to reach out to us if you have any questions or concerns.

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

Do you have questions or comments about this topic? Share in the comments and we’ll answer.

81 Comments

  1. Alicia

    How long does a Paternity takes before no good check the blood test

    Reply
    • DDC

      Hi, Alicia. I’m not sure I understand your question?

      Reply
      • Katy

        If drinking alcohol will it mess the results up?

        Reply
        • DDC

          Drinking alcohol prior to swabbing will not change the DNA, no.

          Reply
      • Ivy

        My son was mouth swabbed for his paternity test. If I would’ve transferred my saliva on the inside of my sons cheeks, would that have altered the paternity test results?

        Reply
        • DDC

          Hi, Ivy. If for whatever reason the lab detects two separate people’s profiles on one or more swabs, testing is immediately suspended and results are not issued until fresh samples are obtained.

          Reply
          • Ivy

            That does not answer my question. Let’s say I was not swabbed for this test because I refused. Then what?

          • DDC

            Your question was about adding DNA to someone’s mouth and I believe I answered that. As for this question, if you refuse to participate in a court-ordered test, then it is very possible the court would rule in the other party’s favor.

          • Ivy

            How would the lab detect my saliva if they did not swab me though? Is there not a yes or no answer on the matter if I would’ve inserted my saliva on the inside of my child’s cheek before his mouth swab would that have altered the Paternity test results?

    • Patricia

      Can a swab DNA results be inconclusive?

      Reply
      • DDC

        Hi, Patricia. I assume you are talking about a paternity test, correct? There is no good reason for any accredited lab to provide inconclusive results for paternity nowadays. If the standard panel doesn’t yield a conclusive result, then the lab can test additional markers or ask to add the mother’s DNA to the test. Whether the sample is swab or blood or other type of sample, this holds true.

        Reply
  2. Brittaney

    Hi, I ordered dna test today. How long will it take for me to receive my kits? I live in Michigan and my Dad is in Arizona.

    Reply
    • DDC

      Hi, Brittaney. If you didn’t choose express shipping, it takes 5-10 business days for USPS to deliver kits.

      Reply
    • Nicole

      I was only able to collect 2 swabs for one of the people being tested. Can I send the 2 swabs for the one person and the 4 swabs for the other person?

      Reply
      • DDC

        Hi, Nicole. Hopefully there is enough DNA on the two swabs to complete testing. If not, we’ll reach out and request more.

        Reply
  3. Ricky

    Can a swab be used on a drink to make someone the father

    Reply
    • DDC

      Hi, Ricky. No, that method would not provide enough DNA to conduct a paternity test.

      Reply
    • Ashley

      We did a swab Dna test but did not swab my daughter for the allotted time? Will the test still be accurate?

      Reply
      • DDC

        Hi, Ashley. If a test report is issued, then the delay in submitting swabs wasn’t an issue. If the daughter’s swabs were contaminated because they were kept too long prior to sending them to the lab, this doesn’t affect results, no report is provided until new swabs are obtained.

        Reply
  4. Brobro

    How soon will you call back of more dna is needed

    Reply
    • DDC

      You are notified via email or text immediately.

      Reply
  5. Treva

    If a newborn was tested but saliva was collected and swab didn’t touch the cheek can it alter the results?

    Reply
    • DDC

      Hi, Treva. No, it won’t alter the result, but there may not be enough DNA in the saliva to complete the test. The reason we ask for cheek cells instead of saliva is because they are DNA-rich. If it turns out there is not enough DNA to complete testing, the process is temporarily suspended and the lab will ask for new samples. If there is enough DNA in the saliva after all, then you’ll be issued a results report.

      Reply
    • Ash

      The representative I spoke to on the phone knew how far along I was. But when I gave a blood sample my technician was wondering if it was too early. Would I have to pay for another test if this is true?

      Reply
      • DDC

        Hi, Ash. We can do testing as early as 7 weeks. If it turns out there is not enough DNA in your blood sample to complete testing, we would schedule another blood-draw appointment in 2 weeks. And no, there is no extra charge.

        Reply
    • Reece

      Hi I currently done a swab but a lot don’t add up and I’m feeling abit confused I understand a dna cheek swap is very accurate my results came back that I am not the father due to 6 out of 14 cells not being the same as me but I’m confused on how they came up with a result on that amount ?

      Reply
  6. Sylvia

    Can the alleged father’s mother take the dna test to determine paternity

    Reply
    • DDC

      Hi, Sylvia. Yes, we do grandparent testing. Receiving conclusive results is much more optimized when the mother of the child also contributes her DNA. For more info, please contact one of our DNA specialists for a free, no-obligation consultation at 800-681-7162 (M-F, 8 am to 8 pm Eastern).

      Reply
  7. Devin

    My child is only a year old and they kept biting and licking the swab while I was swabbing her cheeks, is that Going to interfere with my results ?

    Reply
    • DDC

      Hi, Devin. As long as you also got enough cheek cells on the swab, biting and licking won’t make a difference.

      Reply
  8. Makeba

    How many marker do your test

    Reply
    • DDC

      Hi, Makeba. For paternity we test a minimum of 20 + the sex chromosome.

      Reply
  9. Prudence

    I once did the paternity test, and it was taken to gamany and the result came one month later, I didn’t get the right result. Can you please do something about it.

    Reply
    • DDC

      Hi, Prudence. For any questions about a past test, contact us directly at 800-831-1906 during business hours.

      Reply
  10. Patience

    Hi, I did the paternity test and it was a buccal and I ate and drink 5 min before my test and I didn’t get the right results. Can you please do something about it.

    Reply
    • DDC

      Hi, Patience. Eating and drinking before swabbing cannot change the DNA or change a test result. The only thing that can do is adversely affect the quality of the sample. If you were issued a results report, then eating and drinking was not an issue.

      Reply
  11. Brandon

    Is there a such thing as leaving the swab out to long to dry? Could it potentially change the overall results? If so how realistically would the dna be ok before becoming contaminated?

    Reply
    • DDC

      Hi, Brandon. If a sample is kept in a cool, dry place in a paper envelope (not plastic), then it is viable for paternity testing for about 6 months. A contaminated swab doesn’t “change” the DNA and therefore affect results; it can only make it difficult for technicians and robots to extract enough DNA for testing. If swabs are contaminated, testing is suspended without issuing results, and new samples are requested.

      Reply
      • Daniela

        My daughter had a soda and chips 2 hours before and drank water and chewed gum right before taking the paternity swab test. Could that mess with the results?

        Reply
        • DDC

          Hi, Daniela. Food/gum cannot change the DNA itself; the only effect it can have it to contaminate the swabs so that DNA cannot be extracted. If you were issued results for your test, then eating wasn’t a problem.

          Reply
  12. Amanda

    I did dna test and a lot of the numbers matched up but it came back inconclusive! So what could how cause that!

    Reply
    • DDC

      Hi, Amanda. Did you get results back for a paternity test that were inconclusive? Or was it for some other kind of relationship test such as sibling or grandparent?

      Reply
  13. Marsheilla

    Yes my ex-husbands wife wants a DNA test to prove our son is his however my son is with him at this time if the kit was sent to his house if the alleged father swabbed his own mouth for his sample and the child’s sample would the test be able to pick that up because I have told him the child is not his but he insist he is

    Reply
    • DDC

      Hi, Marsheilla. Yes, if the alleged father submits his own sample as the child’s the lab would be able to tell right away that both the possible father’s and the child’s samples are for the same person.

      Reply
  14. Courtney

    I never got a receipt for payment in my email. Could they possibly have the email wrong? I want to make sure you have the right email in case I need to be alerted that the results were contaminated or I didn’t swab the cheek enough for the cells and I have to swab again. Thank you!

    Reply
    • DDC

      Hi, Courtney. Please check your spam folder in case the receipt went there. Your email address is correct in our system.

      Reply
  15. Rowena

    Mine shows 20/20 number match at least 1 number from my child, but it also shows 14/20 match from my husbands, how can he not be the father when I got pregnant December and had my baby September? Is your DNA test wrong? I don’t know where my other comment went

    Reply
    • DDC

      Hi, Rowena. It’s not unusual for two unrelated people to match at 14/20 loci. What is essential to establishing paternity is that the possible father match at ALL loci, like you do (with the possible exception of a genetic mutation). You can be sure the report provided was correct for the DNA samples we were given to test.

      Reply
      • Cloé

        I took a paternity test without the mother. And there was 20 matcing loci between child and father. But if you say that this can happens for Two unralated people. Is my test accurate?

        Reply
        • DDC

          Hi, Cloe. Without having your report in front of me so I can see the data, I cannot determine whether there were indeed matches. You’re welcome to contact us privately via our Facebook page, where you can upload your report: https://www.facebook.com/DDCPaternity

          Reply
          • Cloé

            The test result was 99,999995% and the CPI number was 23 066 188. But could it just be a coincidence that all of the 20 loci was matching?

          • DDC

            The chances of that is 23,066,188 to 1. That’s what the CPI tells you…it is the odds that the result is a coincidence and that an untested man with the same racial background as the tested man is the father. Yours is an extremely conclusive results…no worries.

  16. Ceana

    I leave in texas were the weather was bad this week I took the test last week but wasnt able to mail it till now well it still be good or do I have to redue it

    Reply
    • DDC

      Hi, Ceana. When kept in a cool, dry place, swabs can remain viable for up to 6 months, so no worries!

      Reply
    • Taylor

      Can swabbing the baby’s mouth with the father’s swab cause a positive reault

      Reply
      • DDC

        Hi, Taylor. The lab would be able to tell that the DNA for the child is the same as the DNA that is supposed to be for the alleged father.

        Reply
  17. Chynna

    Hi i swabbed all 3 participants 10/26/2020, is it too late for me to send it in now?

    Reply
    • DDC

      Hi, Chynna. As long as the swabs containing DNA have been in the paper sample envelopes (not in the plastic packaging the swabs came in or in a baggie) and they’ve been kept at room temperature or in the fridge, they should still be fine.

      Reply
      • Cris

        Im ordering a kit right now for my peace of mind but he previously ordered from a site without reviews and which wasn’t accredited. He sent in my blood sample (obtained by pricking my finger and half filling a half inch vile) after leaving the samples in the glovebox for 3 days.Can that blood sample resaltó be reliable?

        Reply
        • DDC

          Hi, Cris. People should always (ALWAYS!) deal with an accredited laboratory. The results of a paternity test are too important.

          Reply
      • Lucy

        Can you put the swabs in the fridge until you are ready to ship them in?

        Will it be a risk of contamination in the fridge if I wait 30+ days?

        Thanks

        Reply
        • DDC

          Hi, Lucy. As long as samples are kept cool and dry, they should be fine. We do not recommend freezing them, however.

          Reply
        • Amber

          I left my dna sample in my window of my car for a week and a couple days my results came back negative is this correct

          Reply
          • DDC

            Hi, Amber. Leaving a DNA sample in a car wouldn’t change the DNA…it can only possible contaminate the swabs, making it difficult to extract the DNA. Since you were issued results, contamination was not a problem.

  18. Lauren T

    I put the cheek samples back in the plastic envelope before the paper envelope. I still got results back though. Should I not trust those results?

    Reply
    • DDC

      Hi, Lauren. You were lucky your samples weren’t contaminated by mold, which is what can happen when cheek samples are put back in plastic for shipping. Since you were issued results, contamination wasn’t a problem and you can trust your report.

      Reply
  19. Sonia

    My son took a dna test but we dealing with crooks she told my son his mouth was too dry and she was serious bout it one of her friends wanted the little girl I believe she swab her on mouth and the test came back not his and she is soooo much like my son looks and all I really needs the true what can do about it!!!!

    Reply
    • Sonia

      They want let him take another test that not right I had her from a new born on up she’s six now and they want give her back because of their fake test I need help!!!!!!!

      Reply
      • DDC

        Hi, Sonia. I suggest you do a legal test instead of an at-home test. That way, a chain of custody is maintained, IDs are checked, DNA collection is witnessed, and you results are court admissible. Contact our experts to discuss your options…the consultation is absolutely free and there’s no obligation: 800-929-0847 (M-F, 8 AM to 8 PM Eastern).

        Reply
    • Elainey

      Hi I. Did a kit a week or so ago an it came back the guy wasn’t the father but my baby looks just like him all the way an when he did the test he put two mouth swabs in his mouth at one time an I walked out an left him to swab the babies mouth an I don’t understand how the results came back that he is not the father can the results b wrong bcuz he used two mouth swabs at one time on one side of his mouth

      Reply
      • DDC

        Hi, Elainey. No, swabbing the inside of the cheeks with two swabs at once wouldn’t affect the results one way or the other. You can be sure the result is correct for the samples provided for testing.

        Reply
  20. Samuel J

    If a nonstandard sample (toothbrush) was submitted for the child, and the father accidently touched the toothbrush in packing the sample for submission, could it lead to a false postive for paternity (i.e. the father’s seperate DNA bucolic sample becomes a match for his own DNA contaminated onto the child’s toothbrush)? Or does the lab have a way to ensure the two DNA samples came from different people (i.e. they match on some markers on not on others)?

    Reply
    • DDC

      Hello, Samuel. Yes, the lab would discern if a single sample contained DNA from two different people.

      Reply
      • Samuel

        Hi, perhaps I didn’t word my question correctly. I’m not asking if the lab can discern between two people on one sample. I’m asking if the father contaminated the child’s toothbrush with his own DNA, is it possible the lab might detect only the father’s DNA on the toothbush, and then match that to the father’s own bucolic sample, and then call that positive for paternity (i.e. they were really matching the father’s DNA to his own DNA)? Or is it the case that the lab has a way of ensuring the DNA from the two sources are NOT from the same person? Thanks again.

        Reply
        • DDC

          Yes, the lab has ways of ensuring DNA from the two sources are NOT from the same person. By the way, a toothbrush as a source of DNA for paternity testing is not likely to pass a viability test. A cheek-swab sample is always viable.

          Reply
  21. Star

    I have a question about swabbing, so like what if the father and child swabs are mixed up, will the dna still be accurate? The father forgot to put names on the envelopes before putting the swabs in the envelopes so he took a guess of which was which.!

    Reply
    • DDC

      Hi, Star. If the child is also a male, there won’t be an issue. If the child is a female, the lab will halt testing and contact test participants if there is a female’s sample included in the envelope that is labeled as being for the possible father.

      Reply
      • Star

        Yes, the child is a female. Thanks for the answer. It was very helpful.

        Reply
  22. Borle

    What happens if the swaps of the father and the swaps of the son touch. Will this be a positive result or contaminated

    Reply
    • DDC

      Hello, Borle. The lab would detect two separate DNA profiles on a single swab, immediately stop testing, and request new swabs from test participants.

      Reply

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