Your DNA paternity test results will give you the conclusive results required for your peace of mind. The result will provide a lot of detail regarding the testing process and what is specifically is analyzed on your DNA. The results will either be an exclusion or a non-exclusion of paternity.  The paternity test relies on the analysis of 16 genetic loci which are in turn used to calculate what is referred to as a combined paternity index.

But what are genetic loci?

Our DNA is very much like a long reel of string. There is a vast amount of genetic information on our DNA; due to this, scientists only take specific locations of the DNA referred to as loci (Singular Locus).  Studies of these loci have concluded that these DNA sections or fragments differ between individuals in a population. They refer to these differences as alleles.

The DNA test report will show the analysis of all 16 of these loci for each individual taking part in the test. Each locus will have two numbers representing 2 alleles; one allele inherited from each of our parents. In cases where alleles are homozygous (the same) there will only be one number displayed. The analysis then involves comparing the alleles between people taking part in the test and seeing which match and which do not.

In a paternity DNA test, the child might display, on one of the 15 loci tested, alleles with numbers 15 and 10. If the mother is tested, she might have alleles on that same locus with numbers 15 and 9. Since the laws of heredity dictate that we inherit half of our genetic material from one parent and half from the other, we may conclude that allele number 15 was inherited by the child from the mother; they have this allele in common. This means that the other allele, 10, must have been inherited from the father if he is the child’s true biological father.

For paternity to be a definite inclusion there would have to be a total of 15 matches between the father’s and child’s loci.

The 16th locus: the amelogenin gene

Although we test 16 loci in a paternity DNA test, we actually only require 15 for a DNA paternity test. The amelogenin sex gene (one of the sex-determining genes), the 16th locus tested, is not actually part of the test required to confirm paternity. However, we test this added gene as a means of quality control. It tells our scientists that our clients have not made any errors, accidentally or deliberately, when placing swabs into the envelopes and that they have labeled everything correctly for us.

The Combined Paternity Index in paternity testing

For each genetic locus tested our scientists work out a paternity index. The analysis attempts to calculate the chances that a genetic marker passed on to a child has been passed on by his or her biological father and not another random individual in the same ethnic group. When all 15 paternity indices are completed, scientists take all 15 and multiply them together to get the Combined Paternity index. 

The test relies on exclusion and thus, it will determine that 99.99 percent of the male population does not have the child’s same genetic makeup.

If the percentage probability of exclusion is 0%, this means that the father’s DNA is different to the child’s and he thus, cannot be the child’s biological father. The child’s biological father will have a figure of 99.99%.

You can read more and view a sample DNA test result by clicking here.

The oral swab and other DNA samples

We encourage the use of the oral swab for paternity testing due to the ease of use and DNA extraction associated with saliva samples. However, clients may sometimes wish to use discrete samples, such as hair, nails, cigarette ends or blood. These samples provide different success rate as DNA extraction may be difficult in some samples and thus, there could be a chance of the sample not providing any DNA or too little to conclude the test.