How to Interpretate DNA Paternity Test Results

Many people think that a DNA paternity test will give a “yes” or “no” answer. The truth is that it is slightly a bit more complicated than that. In the vast majority of tests, either an “inclusion” or “exclusion” result will be reported.

What an Inclusion Means

An inclusion is reported with a probability of paternity (POP) of 99% or more and a match is found at all genetic markers tested. In an inclusion report, it is stated that the alleged father “cannot be excluded” as being the biological father of the tested child. These three words often create a lot of confusion. This wording is used since an inclusion can not ever be reported at 100%. However, the combined paternity index (CPI) should also be looked at, as it can help to make the results more understandable. First though, it should be understood that the bare minimum for reporting an inclusion result is with a POP of 99% and a CPI of 100 (alleged father and child only) or 500 (alleged father, child and mother). Since our laboratory utilizes an advanced analysis of fifteen genetic markers as a standard, we normally see POPs and CPIs far exceed the minimum requirement. So, when the CPI is say, 100,000, it can be interpreted as a 1 in 100,000 (of the defined male racial population) certainty that the alleged father is the biological father of the tested child.

What an Exclusion Means

An exclusion is reported with a POP of 0.00%. In an exclusion result, it will be seen that at at least two genetic markers, there is a non-match. In an exclusion report, it is stated that the alleged father “was excluded” as being the biological father of the tested child. When an exclusion is reported, a second, independent test will be performed to confirm that the exclusion can be duplicated.

Other Possibilities

Another possible result may be an inclusion with a mutation. In most cases, an inclusion result means that at all tested genetic markers, a match is found. However, sometimes an inclusion can be reported when all but one marker has a match (or, in rare cases, two). Known mutations have a specific frequency in various racial populations and, often, that frequency is low. So, when the mutation frequency is figured into the formula for calculating the POP, it can possibly cause the POP to fall below 99%. To confirm mutations, it is always recommended that the mother test, if she has not already, or to perform extended testing of additional markers.

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Paternity Testing 101: a Simple Guide for a Complex Procedure

In movies and soap operas, paternity tests are often carried out in the direst of circumstances.  In reality, paternity tests are quietly carried out in many homes around the world, confirming or denying what families have suspected.  Whether the paternity testing has destroyed a family, or brought it closer together, it will certainly bring the truth to light.

A paternity test is a simple, non-invasive procedure that can be used to determine who the biological parents are.  There are many reasons why you might need to carry out paternity testing.  Peace of mind is the most often cited reason for seeking out DNA tests to determine the father of a child.  If the mother of the child has been intimate with more than one man, or is suspected of infidelity, the only way to determine who fathered the child is through DNA testing.

Paternity tests: where to start

Once you have made the decision to have paternity testing done, you need to determine the company you feel most supportive working with.  If you need paternity tests done, you can start with some simple searches online.  Equip yourself with knowledge about the procedure, the methods to test and the possible legal ramifications.  If you feel to you can talk to your GP about the tests and what will be required.

Taking the tests: what do you need

Once you have carefully considered the possibilities, it’s time to take action.  If you will be needing the test results in legal proceedings, you will need to go to a certified lab.  While lab tests can cost anywhere from a few hundred pounds to a few thousand, these results are considered to be official and can be used in court.  If you are unsure that the results will bring a need for legal action, you can consider ordering an at home test online.  Thanks to developments in the world of medicine and science, paternity testing is very easy.  All accredited labs should provide 99.99% accurate tests online that can be taken at home or for legal use.  A few clicks of a mouse and your home paternity testing kit will be on its way via express mail.

The aftermath: getting support

Whatever method of testing you chose, the chances are you will have to wait 5-10 days (in many cases more).  This can be a trying time for even the most trusting of people.  While you might have initially only been acting on a hunch, the next few days can be difficult as you try to figure out what will happen if the tests come back negative. Our advice is to try not to let your mind carry you away.

It’s during this time that people often start seeking legal advice.  What recourse will you have if it turns out that in fact little John or Sarah is not your child.  What will this mean for you happy little family?  The answers are not clear-cut, and every situation is different.  It can’t hurt to schedule an appointment with a lawyer to discuss your options.  While you are scheduling appointments, a trained counselor might also be a good idea.  Gain some insight into what caused the situation, and how you are feeling about it, before you need to break the news to often, completely unsuspecting family members.

By getting a paternity test, you are taking your future into your own hands.  Erase all doubt about the paternity of a child within a few short weeks.  The peace of mind that follows this difficult decision is fact.  But do remember to make sure that the DNA Test is in the best interest of the child.

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Dna Paternity Testing of Related Potential Fathers

DNA paternity testing of related potential fathers is not uncommon, although paternity in such cases is more difficult to prove beyond doubt. It is frequently possible if the relationship is known prior to testing, though in some such cases other evidence is generally required before paternity can be legally ascertained.

While positive DNA tests can be accepted as positive evidence of paternity in the vast majority of cases due the statistical improbability of potential fathers having the same DNA profiles, the situation is complicated if the possible fathers are related. It isn’t uncommon for brothers to be involved in a parentage dispute, or even for the mother to have the DNA test carried out privately to determine which is the father of her child.

In normal paternity disputes, whether or not DNA profiling is acceptable as the sole evidence depends upon the circumstances of the case, and it is generally wise to be able to prove the likelihood, or even just the possibility, of the mother and the possible father coming into contact with one another. In Islamic law a paternity test is not sufficient, and other evidence, preferably that of witnesses, is necessary.

The Legal Aspects

Where DNA paternity testing is to be used in evidence, courts will generally insist on a legal paternity test where the collection of the sampling is carried out by an authorized professional and the identity of the subject legally determined. Home DNA testing, or DNA tests on samples presented by the subject, is not admissible as evidence. The probability of paternity accepted as definitive proof varies from state to state, although a probability of 99% would seem reasonable where there is no doubt as to the source of the sample, and where no complications such as rape are involved.

The fact that parentage has been discounted in 99 men in 100 is a more positive identification of the father where there are limited possibilities than were the father potentially any individual in the general population such as occurs with rape. In that case a probability of 99.9% or higher would be more definite, together with additional proof of the likelihood of the suspect being in the vicinity.

Such probability is determined largely by the accuracy of the test that depends upon both the way it is carried out and the number of DNA indicators used (a good average would be 16), and is frequently as high as 99.99% or more. It also depends on whether the sample of the Mother is included in the testing or not, as this will help to obtain a much higher level of probability.

Common DNA between Family Members

DNA tests on related potential fathers are no different from those carried out on any other subject: it is the results that could potentially create problems. Take the case of first cousins: they share 12.5% of their DNA and so it will be more difficult to prove parentage. This sharing of DNA increases to 25% for uncles, nephews and half-brothers, and to 50% for sons, fathers and brothers of the person being tested.

DNA paternity testing on different members of the same family is not an uncommon situation, and can occur for a number of reasons, including:

a) Parentage of pregnancies arising from consensual and non-consensual relationships, although the former is by far the more common of the two.
b) Two family members each claiming parentage, whether or not the mother is claiming one or neither to be the father.
c) A brother desiring confirmation that he is the parent.
d) The mother, or potential mother, having a private test to assure herself as to who is the father.
e) A grown child confirming parentage, particularly where an inheritance could be involved.

There are others, but these are common reasons for legal and home DNA tests being carried out where potential fathers could be related. Standard DNA paternity testing statistics are based upon unrelated members of the public, and unless the laboratory carrying out the DNA testing has been informed of the relationship, the test results could be misinterpreted.

The Case of Identical Twins

Nevertheless, it is possible to test additional DNA markers if any of the above relationships are known, but not in one specific case. This is the case of identical twins. Normal twins occur when two eggs are fertilized by two sperm, and are no more alike genetically than were they siblings born years apart. Identical twins, however, are formed when one egg is fertilized by one sperm and then splits into two halves within the first 14 days for no known reason.

These twins share an identical genetic make-up and so their DNA is identical and indistinguishable from one another. There is no test that can determine which is the biological father of a child. Unless one is excluded for some reason, either could be the father and that is all that DNA testing can prove. The court would have to disregard DNA results and use other means to determine paternity.

Old-fashioned policing, therefore, still has a part to play where the related potential fathers are identical twins. Apart from this specific case, DNA paternity tests are not entirely foolproof since they rely on probability, but are virtually conclusive where you simply want confirmation of paternity. In such a case, a likelihood of 1 in a 1000 is a virtual certainty and where confirmation is required between a limited number of candidates, a 99.9% DNA genetic testing result is legal confirmation.

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