Unexpected Results?

What If Results Are Unexpected And Surprising
A note of caution about the statistical probabilities that are reported when there is a match and also about reported exclusions when there is no match. Even if probabilities appear high or are expressed as certainty, be sure to make checks if the result is surprising to you and you have reason to believe that it is misleading or wrong.


Probabilities of paternity are calculated assuming that the chance of paternity is 50:50 before the test is done. If you are very sure that the tested man is not the father and you get a report back suggesting that he is, then speak to your tester and ask their advice. Although very rare, coincidental/chance matches do occur. Your tester will often be able to suggest additional tests to check the result or, if they can’t, you should consider going to another company for more tests – but make sure the second company use a different set of tests compared with those already done. Of course there is likely to be additional charges but you may decide it is worth it especially if the result has serious impacts on you, your family and the people that you care about.

Similarly, if the result comes back and the tested man is excluded as the father when you are sure that he is, make enquires with the testing company. Inadvertent sample mix-ups can and do happen both at the sampling stage and also within laboratories during the test.

No laboratory is perfect even if they are responsible and properly accredited. Samples are analyzed in big batches, sometimes as many as 80 samples in a batch. This isn’t usually a concern but it is possible for samples from different customers to be accidentally switched. If a sample is switched then it almost always results in a false result that says the questioned father is excluded as being the true father.

Some laboratories run every test twice to ensure it is correct and others automatically re-test samples every time an exclusory result is obtained. Ask them if duplicate testing has been done. If it hasn’t, ask them to do so, if they wont do it free of charge then you might be better to pay for a complete re-test which will not only check the lab process but also your own sampling and sample labeling.

If you think something has gone wrong with your own sampling and labelling then it is best to start from the beginning. If you can, take your samples together with the others to be tested but take them one at a time. Label and fill out the details of each, one at a time, and check each other’s details. Alternatively, you can pay for a legal test and involve a neutral, trusted third party who will confirm the samples are accurately labeled and correctly documented.