Everything You Need To Know About DNA Paternity Test Results

DNA paternity tests are commonly used to determine the biological relationship between a father and child. The test involves comparing DNA samples from the father and child to find out if they share 50% of their DNA, indicating a biological connection.

In this article, we will discuss everything you need to know about paternity results.

Which Samples Are Used In Carrying Out A Paternity Test?

The two main samples used in DNA paternity tests are blood and cheek swabs because they have an accuracy probability of 99.99%. However, if the DNA candidate is deceased, hair can be used as a sample for a paternity DNA test.

Blood Tests

Blood DNA tests are commonly used in both home DNA test kits and DNA laboratory facilities. Blood samples are drawn from the potential father and child, and their DNA makeup is analyzed to find similarities.

Cheek Swab

DNA paternity can also be determined using cheek swabs. This can be collected by swabbing inside the cheek of a potential father and child to collect the buccal cells.


Hair can be used to test for paternity, but it’s the least accurate method. However, if a person is deceased and there is no other way to collect blood or saliva samples, a hair follicle can be used to determine the paternity result — but it will be more expensive than blood or cheek swabs due to the complexity of the test.

What is a Negative Paternity Test Result?

A negative paternity test result means that the possible father and the child are not biologically related. To put it into context, if the child’s DNA profile has two or more DNA loci that don’t match the other person, they’re considered unrelated.

However, this is not always conclusive since a DNA test result can also turn out negative if either the father or child has a DNA mutation or disorder. But that is unlikely to happen in 99% of paternity test results.

What is a False Paternity Test?

A false paternity test result happens when a DNA test incorrectly concludes that a father is not the biological parent when he is or vice versa. Some of the factors that contribute to false paternity tests include:

Human error

A false paternity test can often be attributed to human error such as mixing up DNA samples or mislabeling them. If the samples were not collected properly, it can also lead to inaccurate results. Additionally, the DNA test results could be misinterpreted to alter the conclusion.false positive dna result illustrations


If you’re not extra careful while using a home test kit, there’s a chance of getting the wrong results due to contamination. This often happens when you sneeze or cough while handling DNA samples. The contamination can also happen if the samples come into contact with another person after he/she touched their mouth, nose, or face. As a result, new DNA could be mixed up with a sample and cause a false positive.

However, you can prevent contamination by wearing face masks and gloves while collecting paternity test samples.

DNA Mutation

In some rare cases, DNA mutation can cause false paternity test results since the mutation caused the child’s DNA makeup to differ from that of the father. For instance, if the child has chimerism, the DNA results could be false since they have two sets of DNA that probably won’t match with the father’s.

Related Candidates

If the possible father has an identical twin brother, the paternity test could show that both twins are the child’s father. This is because some twins share a genetic makeup of up to 99.9% with their twin brothers. In this situation, you should disclose if you have a twin sibling before taking the test.

Technical limitations

False paternity results could also be attributed to technical limitations. For example, if you use hair as a DNA sample, you only have an average success rate of 60% because of the complicated DNA extraction process. On the other hand, if you use blood or cheek swabs to test for DNA you’ll probably have a success rate of almost 100%.

How to Read Paternity Test Results?

When the paternity test results come out the results will either read “not excluded’ or “excluded” as the biological father. “Not excluded” means the possible father is biologically related to the child. On the other hand, if the results read “excluded” it means that the possible father is not biologically related to the child.

The locus column of the results compares more than 20 different locations of the father’s DNA and the child’s. If the loci match, it means that they share the DNA in that loci. If they don’t match, it means that they don’t share DNA at that location.dna test results

Another term that appears on the results is allele, which is a variant of a gene or a DNA segment. Alleles are used to determine paternity by comparing their lengths at each locus. If at least one of the child’s allele lengths is at each locus, it means that they’re biologically related.

Beyond that, the test results have a section that reads “combined paternity index.” which is a number that represents how likely it is that the possible father is the true father, compared to a random man from the same population. The higher the number, the more likely he is the father.

know about how to understand paternity test results

How Reliable is a Paternity Test?

Paternity tests are almost 100% accurate at determining whether a father and a child are biologically related. Nevertheless, if you’re using hair samples for the DNA test, the result will only have a 60% chance of being accurate.

How Long Does it Take to Receive Paternity Test Results?

Most DNA test facilities take between 3 to 5 days to deliver the results. However, expedited options are available for an additional cost, which can provide results within a day.

On the other hand, prenatal paternity tests such as CVS or amniocentesis may take longer since they require a more complex DNA extraction process.

How Much Does a DNA Paternity Test Cost?

The cost of a DNA paternity test depends on various factors including the chosen facility, the intended use of the paternity test results, and the DNA test sample being analyzed. For a home paternity DNA test kit, the price range is typically between $60 and $200. In contrast, a legal paternity test, often used for child support claims, often costs between $300-$500.

However, if you use hair as a DNA sample for the paternity test, it will be more expensive and could cost over $600.