Our Most Frequently Asked Questions

How does your parental DNA test work?

A child inherits their DNA from their mother’s egg, containing 23 chromosomes, and the father’s sperm, also containing 23 chromosomes. Therefore each contributing parent determines half of the child’s DNA. The child (and any human) has 23 pairs of chromosomes.

Every location (“locus” – plural “loci”) in a chromosome pair has a specific DNA sequence for every chromosome. A parental DNA test identifies the DNA sequences specifically for multiple loci in the mother, child, and father.

If the mother and father are confirmed as the parents of the child, the DNA sequences at each locus of the child’s chromosomes must have been inherited from each parent. Determining paternity and maternity is possible from these DNA sequences.

For more information, see Understanding a Paternity Test Report.

Where do the DNA tests take place?

You are able to order Home DNA Kit or Paternity Test Kit to complete at home or contact us to help you to arrange sample collection at various facilities across the country.

What accreditaton criteria do you use to make sure DNA tests are performed correctly and DNA test or paternity test results are accurate?

GTL follows strict criteria governed by ISO 17025 and the AABB for performing all DNA tests. As 16 genetic markers are used, test results are usually absolutely definitive. In the event of any uncertainty, possibly as a result of poor sample collection, the test will be repeated.

GTL offer a Paternity Test Accuracy Guarantee and as a respected DNA testing facility, we adopt specific practices to protect against any tampering of collected samples and subscribe to always maintaining the confidentiality of our customers.

Is there a difference between an accredited and an unaccredited DNA test?

GTL have addressed this very concern by producing a dedicated article on Why DNA Accreditation is Important.

How are Court Approved DNA tests different from Peace of Mind DNA testing?

The laboratory testing processes for Court Approved and Peace of Mind DNA tests are exactly the same. The difference is that Court Approved tests require a witness, proof of identity and special chain of custody procedures. The informational or Peace of Mind DNA Test is not legally binding because there is no proof that samples have been collected from the correct participants.

The Peace of Mind test is intended to be a discreet and private way of allowing families to resolve any questions without involving other parties. The Court Approved DNA tests require that an independent witness, such as a GP or health professional, oversees the sample collection process and is able to verify photo ID and maintain chain of custody.

What is buccal swabbing and is it as accurate as a blood sample?

A buccal swab refers to a process whereby a sample of cheek cells are collected by simply rubbing a swab, similar to a cotton wool bud, on the inside of the cheeks. The process is as accurate as a blood sample as the DNA in question is exactly the same.

Prior to sample collection though, a person should abstain from drinking coffee for several hours, and smokers should rinse and brush their cheeks with a toothbrush before swabbing.

Does the mother need to take part in a paternity DNA test?

A paternity test can be performed without the mother taking part but the results are not as conclusive. For this reason, GTL offer an Accuracy Guarantee for a paternity test where the mother is also involved as part of the test.

Why do we need to include a DNA sample from the mother when performing a paternity DNA test?

When it is something as important as establishing the paternity of a child, particularly legal DNA test cases, it is not wise to leave any room for uncertainty. In an ideal situation the mother, child and alleged father should all be tested.

A child inherits half their DNA from their mother and the other half from their father. As the DNA the child inherits from the mother will match the mother’s DNA exactly, the remaining unmatched DNA will match that of the biological father.

Without being able to remove the mother’s DNA from the equation there is a chance that results will not be conclusive, which may require additional genetic marker testing, therefore extending the time and cost needed to achieve conclusive results.

In general, if the mother is available for testing, samples should be collected. Either way, the testing can still be performed and accurate results can be achieved without a sample from the mother.

Can I test more than one child or alleged parent?

Additional family members can be included in tests. See our DNA Tests for information.

Does a child need to be a certain age to perform a DNA paternity test?

A newborn baby can be tested. Using a buccal swab to collect a sample is painless and is not traumatic for the child.

If you wish to test paternity before birth, please see more information on our Prenatal Paternity Test page.

Once the test has been conducted, what happens to my DNA samples?

For inormational or Peace of Mind DNA tests, the samples you submitted to us are destroyed immediately following the release of your results. Should you wish us to retain your DNA samples for longer, we are able to archive them for up to six months subject to payment of an additional fee. If you would like us to archive your DNA samples, please contact us.

For Court Approved DNA Testing cases, DNA samples are archived for six months at no additional cost.

How accurate are DNA paternity test results?

DNA testing is the most accurate method available to establish paternity. Its power is found in its ability to trace the pattern of inheritance for separate regions of the genetic material (chromosomes). From this information, it is possible to calculate a probability of paternity.

This number can reach 99.99999% in some cases. The percentage of random men of the same race that can be excluded as the biological father is also computed for every case.

Some companies test fewer chromosomal locations for the same price (or more) that GTL charge for 16 (15 identity markers plus one to confirm the sex of the person being tested). However, the statistics generated with fewer locations are not nearly as conclusive and in some cases can result in wrong conclusions, such as the father being excluded when, in fact, he is the true biological father.

What is the GTL Accuracy Guarantee for DNA Paternity Test results?

Our Accuracy Guarantee promises such results due to the accuracy of our tests and the standards that we adhere to during the testing process.

Genetic Testing Laboratories are accredited by ISO 17025 and the AABB as a parental DNA testing laboratory. We also participate in annual proficiency testing conducted by the College of American Pathologists three times a year.

Our medical director and director designee also oversee the entire process and personally review and sign all DNA test reports. Our methods and practices give the reassurance that we adhere to the strictest standards possible.

How long do results take to produce?

GTL endeavour to have the results returned in 5 working days from receipt of samples at the laboratory. A shortened processing time of 4 working days or less can be arranged at an additional charge. See our DNA Tests page for more information.

How will my DNA test results be received?

For legal, or court admissible, DNA tests, one copy of the notarised test results and supporting documentation will be posted to you, or a designated recipient, as per your instructions. Further notarised copies are available at an additional cost of £50 each.

Peace of Mind test results will be available to view online as soon as the DNA test is completed and can be downloaded and saved or printed. We do not release results by telephone, email or letter unless you have made prior arrangements for us to do so. DNA test results can be telephoned, emailed or posted for an additional administration fee, currently £5 for telephone, £10 for email, £15 for first class post or £25 for all three.

You may follow your order status and view your DNA test results online as soon as they become available by visiting our Order Status page.

How do I make sense of my DNA test report?

For the majority of cases, test results produce a definitive result. The alleged father is either ‘excluded’ or ‘not excluded’ as the child’s biological father.

Each of the 15 identity loci are analysed indiviudally to calculate a paternity index and all the separate indexes are combined to calculate a ‘combined paternity index’.

For more information, please see our Understanding Paternity Test Results page.

What is the Combined Paternity Index?

The Paternity Index is a number that represents the likelihood of paternity. This number is calculated based on how common the genetic information found in your test result is within your race population.

The Paternity Indices for each genetic locus tested are used to calculate a Combined Paternity Index (CPI) which can result in a 99.999% probability of paternity, or even higher in the case of a true match.

For example, if the CPI is 9,999,987 it means the odds of the tested father being the unique biological father are 9,999,987 to 1.

Can my DNA test results be used in a court case?

Yes, providing you purchase a Court Approved DNA test. The Court Approved DNA tests have additional proof of identity and chain of custody requirements made possible by having your GP or health professional witness the DNA sampling procedure and verify photo ID.

Careful records are maintained on every sample processed and DNA test results should be admissiblein a court of law.

Are the DNA test results confidential?

All DNA test results are held in strictest confidence and released only to you. In addition, the information produced from testing the 15 identity loci only relate to identity and do not reveal any supplementary information of medical relevance.

What about blood sample DNA testing?

IMPORTANT – Your GP or consultant should be contacted for blood sample collection from children under the age of 8 years

GTL offers blood sample DNA testing because it is faster and easier to obtain a sample. The procedure involves a small lancet, used to lightly prick a finger. A small drop of blood is then transferred to a collection card. Buccal swab testing is available at no additonal cost and provides the same degree of accuracy.

Can my DNA Test Kit be sent to me discreetly?

DNA tests can obviously be of a sensitive nature and we are more than aware of this. All our DNA sampling kits are sent out in the post in plain envelopes marked Private & Confidential and with no branding on them, so it will look like a normal letter.

What comes in the Home DNA or Paternity Test Kit?

The Home DNA Testing Kit contains detailed instructions and a consent form to be completed with information about each family member providing a DNA sample. Apart from infants and very young children, each person collects his or her own samples.

The collection process is simple. Buccal sampling should take about 15 minutes for 3 people, and you need to allow an additional 30 minutes for the swabs to dry. Blood sampling takes about 15 minutes for 3 people. The samples need to be placed in their own clearly labeled sample collection envelopes.

All of the DNA samples and consent forms for those involved then need to be placed in the included return envelope and sent back to our laboratory by Recorded or Special Delivery

Do I need to obtain a Court or Doctor’s order for a paternity test?

No Court or Doctor’s order is required to request GTL to perform a paternity test.