Understanding your DNA test results is fairly straightforward once you know what data the results actually give you. For many people, this will be the first time they have undergone any form of DNA test, so the following information will help you to understand the test results.

So that paternity can be determined, samples of DNA from both the child and the alleged father are needed. Sometimes a sample of the mother’s DNA is also included, but it is possible to test for paternity without DNA samples from the mother. These tests are known as “motherless”. If the mother’s sample is included, the results can be more accurate and provide an increased probability of paternity.

When the DNA samples have been obtained, the genetic blueprints are extracted using a form of biochemical technology known as PCR (polymerase chain reaction), and then compared with each other.

Babies inherit 23 chromosomes from their mother and 23 from their father, making 46 in total. Certain genetic markers between the child and the alleged father are compared in a DNA test, to determine whether their genetic makeup is shared, and whether the tested father is actually the child’s biological father.

Depending on your individual needs, there are different Paternity Tests from which to choose. Sometimes, an individual simply wants a paternity test for their own peace of mind, and for this purpose, a Home Paternity Test Kit can be used. If a DNA test is required for legal purposes or is needed in an immigration case, then more stringent collection methods need to be used so that the results will stand up as evidence in a court of law.

In the test, 21 genetic markers are compared between the alleged father and the child to determine whether or not they match. Only 20 of these genetic markers are actually compared, because the twenty first is only included to ensure that there has been no mistake in the labelling of the sample in a home DNA test. This last genetic marker is called the amelogenin sex gene and determines gender. By testing this, the laboratory can be sure that the sample labelled as the alleged father’s is actually from a man and the mother’s sample swabs have not been placed in the wrong envelope in error.

Understanding your DNA test results depends on whether they indicate paternity inclusion or exclude paternity.

The extracted genetic markers from the DNA samples are represented in a table, listing each marker. The report you receive includes this table, and the results for the child, the alleged father and the mother if she is tested, are displayed in separate columns.

One possible result can be paternity inclusion, which confirms that the father who has been tested is the child’s biological father. In this case, the probability will be in excess of 99.99% and the Statement of Results on the report will read “The alleged father cannot be excluded as the biological father of the tested child. Based on the analysis of STR loci listed above, the probability of paternity is 99.99999%”

If the tested father is not the child’s biological father, the results will be exclusion of paternity. The probability of paternity in this case would be 0% and the Statement of Results on the report will read “The alleged father is excluded as the biological father of the tested child. This conclusion is based on the non-matching alleles observed at the STR loci listed above with a DI equal to 0. The probability of paternity is 0%”.

The results are calculated using a complex statistical analysis, known as the Combined Paternity Index or Combined Direct Index. This indicates the probability of paternity from the tested sample, compared with the probability that a random man from the same ethnic group is the father. When the probability of paternity is 99.99% this means that the man who has been tested is 99.99% more likely than a random man to be the biological father of the child.

Please do not hesitate to Contact Us if you require any help understanding your DNA test results.