Can Your Paternity Test Sample Become Contaminated? What You Need to Know

Paternity Test
Written by Nancy

False results in paternity tests are not as common as mainstream media would have you believe!

With time and research, paternity testing technology has become quite accurate, especially post-1980s. But this isn’t to say that there’s no room for error when it comes to testing one’s genes through a paternity test.

Most of the time, any potential errors stem from sample contamination, as opposed to inaccurate science!

So how does a sample become contaminated—so much so that it may lead to inconclusive results? We asked the professionals at Divergent Health, a leading clinic in Calgary to guide us on paternity testing mistakes.

What Affects a Paternity Test Sample?

– Smoking, Eating and Drinking

Typically, your mouth should be clean of food, liquids, tobacco, toothpaste, and any other products when you give a sample.

While foreign particles don’t alter your DNA, they do mask certain genetic traits, which can lead to a degraded result that’s unusable for testing.

When collecting a sample, wait at least an hour before you take it. If you eat or drink anything, rinse your mouth out with water afterward, just in case.

– Spitting on the Swab vs. Swabbing Your Cheek

The reason why cheek swabbing is recommended rather than direct spit is that cheek cells have a more concentrated amount of DNA, versus spit, which may be contaminated with residue or food.

While spit may still be able to provide results, the lab will take a longer time while extracting the DNA. So always swab the inside of your cheek, not your tongue.

– Cross- Contamination

This includes things like dropping the swab, touching the tip of the swab or putting in another person’s swab with your own in the envelope.

These kinds of mistakes don’t typically require a second collection since the lab does catch them early on. But if you want your results to come back in a timely manner, it’s crucial that you follow the right directions.

– Re-using Packaging

The saliva and cheek cells collected using the buccal swab are meant to be kept safe from contamination.

This is why the sample kit is provided with a sealed plastic packaging to keep the sample sterile. However, when the packaging is reused, this lets the wet sample breathe, i.e., come in contact with air.

As a result, mold starts forming almost immediately, which degrades the DNA and destroys the sample.

– Mailing a Wet Envelope

While collecting cheek cells, there is a chance that you might get saliva on the swab as well. However, if there’s too much saliva on the sample, the paper envelope could become a little wet.

This is a problem because envelopes that are damp have a higher risk of ripping open en route. If this happens, you may need to send in a second sample, which may cause a delay in your results. When giving a sample, letting the swab air-dry for a bit will help keep the sample at least partially dry.

Are You Ready to Take a Paternity Test?

Always go with a trusted clinic for your paternity tests, such as Divergent Health in Calgary.

Partnered with accredited labs in the state, Divergent Health offers accurate, fast results. So take care not to make any of the above mistakes and provide a good sample, to make processing easier.

About the author


I’m Nancy and no, I didn’t always look like I do in that picture on the right. My foray into health and fitness began as a brace-faced, 16 year-old who was too afraid to wear a two-piece at the beach because I felt my body paled in comparison to my much more toned friends.

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