Sibling DNA Testing

Sibling DNA analysis is carried out between two or more individuals to determine the probability that they share one or both biological parents. A full sibling test is used to determine if the tested individuals share the same biological mother and father; whereas a half sibling test can be used to determine if the tested individuals share one biological parent (either mother or father). This type of analysis is ideal for siblings who may have been separated from an early age and who wish to receive confirmation that they may be biologically related.

A DNA profile for each individual is produced and the DNA markers are compared: full siblings usually have more markers in common than half siblings, and half siblings usually have more markers in common than unrelated individuals. Statistical analysis is performed taking into consideration the number of matches observed between the tested individuals, the frequency of the observed marker within the relevant population, and whether the clients require full or half sibling analysis.

The calculations performed result in a probability of relatedness:

  • SUPPORTIVE: A result of 10+ provides very strong support that a full/half sibling relationship does exist
  • NOT SUPPORTIVE: A result of 0–1 is not supportive of a full/half sibling relationship
  • INCONCLUSIVE: Results falling within the range 0.11–9 are deemed to be inconclusive because it is not possible to determine if a biological relationship exists between the tested individuals

An inconclusive result could be due to a low number of matching markers shared between the tested individuals. Alternatively, the markers that are shared between the tested parties could be extremely common within the relevant population.

Sibling analysis is not as conclusive as paternity or maternity testing and should be used when it is not possible to perform other types of testing.


You have two main options when choosing a sibling DNA Test:

  • Testing for peace of mind, which produces results that can resolve family relationship questions but cannot be used for legal purposes
  • Legal testing, which produces legally defensible results that are useful for such matters as family law disputes and immigration



If you opt for a Peace of Mind test, we will send you a free sample collection kit. You and the other parties to be tested will collect your own samples following the simple instructions provided. Please note that Peace of Mind test results are not legally defensible.


If you opt for a legal test, your DNA samples will be collected by a neutral third party such as a doctor, a nurse or one of our representatives. This third-party collection is an important element of the chain of custody process, which will ensure that your test results are legally defensible.


Our customer service department is open 8.30 am to 5.30 pm, Monday to Friday. Call our free phone number 01 402 9466 to speak to one of our experts. Outside these hours, please leave a voice message on our answer phone and your call will be returned as soon as possible. Alternatively, you can email us at

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