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How accurate are Paternity tests?

Paternity testing is a highly accurate method of identifying whether a man is a child’s biological father. In this article we look at what can affect test accuracy and how you can be sure that your results are correct.

What is a paternity test?

A paternity test is a type of DNA relationship test that is used to verify a biological relationship between a child and their alleged father.

To perform the test, DNA samples are collected from the child and any alleged fathers using cheek (buccal) swabs: a simple, pain-free method of sample collection that means the test can be performed at any time on a person of any age, including new-born babies and grown-up children/adults.

These samples can then be analysed and compared in the laboratory to identify matching DNA markers (loci) in the DNA samples.

AlphaBiolabs examines short tandem repeat (STR) markers that are specific locations on chromosomes made up of sequences of repeated DNA. These STR markers are highly variable in length between individuals. Each individual has two copies of each STR marker, known as alleles: one is inherited from the father and the other from the mother. By looking at these specific DNA markers in each sample, it is possible to identify which half of the child’s DNA is inherited from the mother and which half is from the father.

When testing the biological father of the child, both the man and the child will share enough identical sections of DNA to confirm a biological relationship.

If the tested man is not the biological father, this will not be the case.

How does a DNA paternity test work?

All our peace of mind paternity tests are performed in the same way, whether you want to verify paternity of an adult, or a baby who has recently been born.

Paternity testing works by comparing a child’s DNA profile with that of the alleged father(s).

An AlphaBiolabs paternity test looks at up to 45 DNA markers (loci) to identify which half of the child’s DNA is inherited from the alleged father.

Every person inherits half of their DNA from each of their biological parents, so such a comparison can help us to establish the probability of paternity.

When testing the biological father of the child, both will share identical sections of DNA at each marker. When the man tested is not the biological father, the man and child will not share enough DNA to verify a relationship.

What can affect the paternity test accuracy?

Our test results are 100% accurate based on the samples we receive into the laboratory. We test up to 45 DNA markers (loci), so you can be confident of getting an accurate result.

As the DNA testing kit for an ‘At-Home or Peace of mind’ paternity test will be sent directly to your specified address, you are responsible for collecting your own samples.

Our paternity test kit contains detailed, simple-to-follow instructions, which, if followed fully, will ensure you collect your samples correctly for accurate testing at our laboratory.

There is a possibility that someone may try to ‘cheat’ the test, by deliberately submitting incorrect samples.  This will result in a false result.

If the test swabs are deliberately or accidentally contaminated in any way, this will result in the need to retake the test.

When the father, mother and child participate in the paternity test, we will provide a probability of paternity in excess of 99.99% thereby confirming the biological relationship, or alternatively confirm with 100% accuracy the exclusion of the alleged father.

AlphaBiolabs cannot know if the samples submitted are from the correct people and a level of trust is therefore needed between the people requesting and taking part in the test. We clearly state that the samples have not been verified and hence the report cannot be used in a court of law.

If you require a DNA test for official matters such as changing the name on a birth certificate, or for child maintenance or custody disputes, you will need to request a quote for a legal DNA test.

Why does the result not show 100% probability?

A paternity test determines whether or not a tested man could have passed on his DNA to the child. A DNA test report usually include two values:

1) the Combined Paternity Index (CPI) – this provides an odds ratio of how much more likely it is that the tested man is the father rather than an untested man

2) the Probability of Paternity is based on the CPI and shows the probability that the tested man is the true biological father of the child.

These values can be calculated with or without the inclusion of the mother’s sample, but it provides even greater certainty when the mother is tested. For example, a test we completed with the mother gave a Probability of Paternity of 99.99999%; removing the mother from this test would have reduced the Probability of Paternity to 99.99%.

High probabilities of 99.99% and above are commonly seen in DNA paternity testing, but never 100%. This is because results are based on statistical calculations. A result of 100% would only be possible if AlphaBiolabs tested every male of the same ethnicity as the biological father. This is why the DNA profiling test report uses the wording ‘provides (extremely/moderately) strong support in favour of paternity’. A probability over 99% means there is relatively no chance that any other man, other than the tested man, is the father of the child. The only exception to this is when the biological father is a close relative of the alleged father, which is why we always ask if this could be a possibility when you register your paternity test.

Are home paternity tests accurate?

Yes, an AlphaBiolabs home paternity test is 100% accurate based on the samples received into the laboratory.

Our paternity test kit contains detailed, simple-to-follow instructions, which, if followed fully, will ensure your samples are collected correctly for accurate testing at the laboratory.

We have performed over ONE MILLION genetic tests since 2004, so you can be assured that our ISO 17025-accredited and award-winning testing laboratory will provide the accurate results you need.

All tests are performed assuming that a close male relative of the alleged father is not the potential father. If this is not the case, you must tell us at the time of ordering the test, as it is recommended that any such relative is also tested to ensure absolute accuracy of the results.

Where can I order a paternity test online?

You can order your Paternity Test online now from just €135, with results in just 2-3 days. results.

Please note: our home paternity test is for peace of mind only. This means that the results are purely for your information and cannot be used for official/legal matters.

Before taking a paternity test, we would always encourage you to think about the potential implications for both you and your family if you do not get the result you want.

If you require a DNA test for official matters such as changing the name on a birth certificate, or for child maintenance or custody disputes, you will need to request a quote for a legal DNA test.

For confidential advice on which is the right test for you, call our friendly and discreet Customer Services team on 0140 29466 or email info@alphabiolabs.ie.

Home Paternity Testing Kits

Order your Paternity Test online now for just €135

Casey Randall AlphaBiolabs

Casey Randall

Head of Genetics at AlphaBiolabs

Casey joined the AlphaBiolabs team in 2012 and heads up the DNA laboratory.

An expert in DNA analysis and a member of the International Society for Forensic Genetics (ISFG), Casey holds an MSc with Distinction in DNA Profiling and a First-Class BSc with Honours in Forensic Science.

Casey is responsible for maintaining the highest quality testing standards, as well as looking for ways to further enhance the service that AlphaBiolabs provides and exploring new and innovative techniques in DNA analysis.

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