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Sibling DNA Testing

Sibling DNA testing is the ideal test to establish if you are full siblings, half siblings, or unrelated. The test is available as an appointment at one of our DNA Clinics. Or you can order a sibling DNA test kit for free from our online store. Also, the sibling test is available as a ‘peace of mind’ or legal sibling test. As a result, the latter option will provide you with court admissible DNA test results.

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How does a Sibling DNA Test work?

As with the paternity test, a DNA profile is produced for each person. The test analyses different genetic locations on the DNA strand. First, the allele (alternating form of DNA) at each location is identified by a number. Next, the DNA profiles of the test participants are then compared.

The logic behind the sibling test is that biologically related individuals should have more DNA in common than unrelated individuals. Therefore, on average the numbers from full siblings will match at more DNA locations than half siblings. In turn, half siblings will match at more than unrelated people.

Frequently Asked Questions

How long does it take for the Sibling DNA test results?

The average analysis time in the laboratory for a sibling test is around three to four working days. But this does not include the quality checks needed for sample integrity or your consent paperwork. So, from receipt of your samples at Crystal Health Group, it takes on average of about three to five working days. If there are any unforeseen delays, for example, such as the paperwork we receive not being quite right, we will contact you as soon as possible to let you know.

How do I order a Sibling DNA Test?

Here are the options available to you:

  • Order a free sibling test from DNA Clinics*
  • Call 0800 988 7107 to make an appointment at a DNA Clinic or order a *DNA self-collection Home Kit
  • Call 0800 988 7107 to arrange a home visit from a sample collection officer
  • You or your solicitor can contact us to organise a legal sibling DNA test for court purposes

* Please note, you can only use self-collection kits for peace of mind purposes only. This test cannot be used for legal purposes.

How accurate is the Sibling DNA Test?

The result of a sibling analysis is based on statistical calculations. As such, this produces a probability indicating whether two individuals are true biological relatives. The statistical analysis is based on factors such as:

  • The number of matches between the DNA profiles.
  • How likely it is that the same allele would be found at that same DNA location, if testing a random, unrelated individual from the same ethnic background.

These calculations determine the most likely relationship between the individuals tested. This could be full or half siblings, or unrelated.

Also, you can improve the chance of a conclusive result for your sibling DNA test. Please call and speak to a Clinical Advisor who will explain the additional options available to you.

Please refer to the disclaimer on this page for further information.


Due to the science of complex DNA relationship testing and the chance nature associated with DNA inheritance, there is a small risk of an inconclusive result with this test. An inconclusive result means that the DNA analysed and compared between individuals does not provide enough evidence to establish the biological relationship being tested. The risk of obtaining an inconclusive result varies due to several factors including, the test participants available for testing, the individual’s specific DNA profiles and how unique or common they are and the number of locations on the gene tested.

It is important that you are aware of the risk of an inconclusive result before ordering or booking this test, as you will be signing consent to confirm your understanding and acceptance of this. Refunds will not be issued for inconclusive results.

However, we will always attempt to achieve a conclusive result for your DNA test. As such, there may be further options available to you to achieve this. These are:

  • The addition of other test participants, including other known siblings or parents. Additional costs will apply after any initial testing has taken place.
  • The standard complex tests analyses 23 locations on the gene. It is possible to test a further 20 locations (total of 43), which increases the chance of a conclusive result. There are two options for this:
  1. If the 43 loci test is ordered from the beginning, the additional charge is only £30.
  2. If the 43 loci test is ordered after a standard complex test produces an inconclusive result, the additional charge is £60.

If you are using the DNA Clinics service and booking an appointment, the above options will be explained to you. If you are ordering a self-collection kit, please call 0800 988 7107 and speak to a member of our team about these options before you order a DNA kit.

Local DNA Clinics, and mobile locations throughout the UK

For your convenience, we have a network of DNA Clinics throughout the UK. As a result, we can provide sibling test appointments for you in your local area. Alternatively, we can arrange for a certified sample collection officer to visit your home or other convenient location of your choice.