Understanding Your Paternity Test Result

The DNA test result will conclusively determine whether the alleged father of a given child is “excluded” meaning not related to the child, or on the other hand, a 0% probability of biological relationship. In cases where the test result conclusively determines that a father is not excluded, meaning there is a genetic relation between alleged father and the child; the result will have an accuracy of 99.99% probability of relationship. Each test consists of a thorough comparison between two or more parties to examine the number of shared genetic material or to be precise, of 21 genetic markers. The father’s DNA blueprint and the child’s DNA blueprint are compared. The resulting number will determine the Combined Paternity Index or CPI.

What is the CPI?

All genetic markers provide by mathematical calculation provide us with a paternity index. These are later combined together to give the CPI or the combined paternity index. The combined paternity index or CPI is an algorithm used to establish the probability of paternity. The CPI, as shown in our sample results, enables us to determine the percentage probability that the tested man is the biological father of the child or is not the biological father of the child. In our DNA tests, we expect a minimum of 99.9% probability in cases whether the man tested is the biological father. If he is not the father, we issue a 0% probability.

The DNA test report explained

Upon receipt of your DNA test samples in our laboratory, the DNA supplied will be sequenced to extract the specific genetic markers, 21 in total. The genetic markers are simply represented in a table with each marker listed. The individual locations or markers are referred to as genetic loci, and there are sixteen distinct loci locations in each human’s genetic makeup*.

Your DNA test report from EasyDNA will show you two columns of results from your specific DNA test. In each human’s genetic makeup, there exist two unique sets of chromosomes: one group inherited from the mother’s side, and the other from the father’s. Each locus on the chromosome is represented by two numbers representing the size of the allele.

For example, Let us take this situation:

The child has alleles expressed as 12 and 16 (remember we already know that one allele is always inherited from the mother and the other allele from the father). Analyzing the father’s sample, we see that he has alleles 16 and 8. It is thus clear that the child has inherited allele number 16 from the father. By elimination, allele number 12 is inherited from the mother. We do this for every one of the 15 markers tested and look for an exact match on each locus for a paternity test inclusion. If there are markers which do not match, then it will be an exclusion.

* analysis of DNA involves comparing 20 genetic markers although we test a total of 21. The 21st marker is the amelogenin sex gene. We test this gene to determine whether samples sent for testing are male DNA samples or female DNA samples.

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