Paternity Testing Process

Paternity Test Results

Paternity test reports provide powerful and often life-changing information. And, while you want the best DNA testing available to answer your paternity questions, you shouldn't have to be a genetic scientist to understand the results. IDENTIGENE brings all the genetic information from your case together in a simple, easy-to-understand, one-page report.

This section explains how to read and understand paternity test results from IDENTIGENE. If you have any additional questions or concerns, please contact us (8 AM to 6 PM EST, Monday through Friday).

The Paternity Test Report

Your paternity test result appears on a single page and contains the following important information:

  • The Conclusion Statement
  • The Combined Parentage Index (CPI) number
  • The Probability of Paternity
  • DNA Profiles for each person being tested

If you're not a geneticist, these scientific terms might seem more than a little intimidating.  But a quick review of each shows how easy the process is to follow.

The Conclusion Statement

The Conclusion Statement answers the question of paternity in a single sentence.  It's the bottom line, printed at the top of the page so it's easy to find. 

A conclusive paternity test result shows one of two possible statements. For example, if we tested samples from JOHN DOE (alleged father) and JAMES DOE (child), our paternity test report might say one of the following:

JOHN DOE is excluded as the biological father of JAMES DOE.

This means that John Doe is not the father of James Doe because the analysis shows that their genetic profiles are not compatible with a paternity relationship.

JOHN DOE is not excluded as the biological father of JAMES DOE.

This means that John Doe is the father of James Doe because the analysis shows that their genetic profiles are compatible with a paternity relationship.

Paternity Testing relies on DNA matching and relationship probabilities to answer the paternity question.  It might help to think of the question this way: Can we be 100% sure that the alleged father is not the father of the child?  Can we rule him out completely?  If we can, then he is excluded as the biological father - in other words, he can't be the father of this child.

If we can't rule him out completely, if he is not excluded, then how strong is the match between the father and child?  How sure are we that JOHN DOE really is the father?  The Combined Parentage Index and Probability of Paternity help answer our question.

Probability of Paternity and Combined Parentage Index (CPI)

You can find the Combined Parentage Index and Probability of Paternity numbers just below the Conclusion Statement on the report.

Paternity testing examines up to 17 Genetic Systems (sometimes called markers or locations) in a person's DNA, checking for matches between the alleged father and the child.  Each match produces a Relationship Index, a number that shows how strong the match is; the higher the number, the stronger the match.

If the alleged father is not excluded (he is the father) we multiply all of the Relationship Index numbers together to produce a Combined Parentage Index, or CPI.  The CPI must be at least 100 to be strong enough proof of paternity for a court of law (at least 200 for immigration cases).  When a paternity test shows that a person is the father of a child (he is not excluded), the CPI is often much higher, in the hundreds of thousands, millions, or even billions - providing solid proof of paternity.

The CPI can also be shown as a percentage or a Probability of Paternity; these two numbers represent the same conclusion.  A CPI of 100 becomes a probability of 99%; a CPI of 200 becomes a probability of 99.5%.  CPI numbers in the hundreds of thousands or millions become probabilities of 99.99% or greater (99.9999%).

DNA Profiles

DNA Profiles for each person being tested show how the CPI and Probability of Paternity were calculated.  A DNA Profile contains a set of Genetic Systems (locations or markers) for each person.  Years of research, including work by top scientists at the FBI and Human Genome Project, make these Genetic Systems extremely reliable for paternity testing. [You can read an in depth discussion about DNA Profiles and how they are used in paternity testing here.]

More Information

While most DNA paternity tests reflect this "text book" example, there are many other factors to be considered. For example, naturally occuring mutations sometimes present more complicated results. Sometimes father and child share many common alleles and, though there are matches at all genetic systems, the CPI value is not strong enough for a conclusive result. In most of these cases, including the biological mother significantly strengthens the test results. That's why IDENTIGENE strongly recommends including the mother on any DNA paternity tests.

If you have questions about your paternity test report or would like more information, please contact us (Monday through Friday, 9 AM to 6 PM ET).