Sibling DNA Tests

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What is a Sibling DNA Test?

Sibling DNA testing is used as an indirect way of establishing the identity of biological parents. The sibling test analyses the participants DNA to determine whether they have any biological parents in common. The sibling test should only be used when the parents in question are not available for testing themselves

  • ISO 17025 Accredited/ 100% Accurate Results
  • Inconclusive rate of 1 in 4
  • Legal Sibling test and Peace of Mind options available
  • Known parent tested for free to improve tests accuracy

The Sibling DNA test is able to establish the following:

Do we have the same father?
Are we full siblings or half siblings?
Are we half siblings or unrelated?
We have the same mother but do we have the same father?

What are the types of Sibling DNA test?

There are typically four types of Sibling DNA Test, depending on the situation known:

  • Full Sibling OR Half Sibling Test– This test is carried out when test participants have one known biological parent in common and want to test whether they also have a second. In most cases, the participants have the same mother and want to test whether they have the same father.
  • Half Sibling OR Unrelated Test - This test is designed to establish whether the test participants share one biological parent. In most cases, the test participants know that they have different mothers but want to test whether they share the same father.
  • Full Sibling OR Unrelated Test – This test is rare and is used to establish whether the participants have both biological parents in common or whether they are unrelated. In most cases, this test is used in cases where the participants were adopted or otherwise separated from siblings at an early age.
  • Combination Sibling Tests – Sometimes multiple siblings exist in a case but within the siblings, there is a mixture of suspected full sibling and half sibling relationships. In these cases, each participant is independently compared to the others.

At DNA Clinics, a Clinical Advisor will work with you to establish exactly what the situation is and what the known facts are, thus determining the correct form of sibling test for your family.

If a KNOWN parent is available for testing, then they will be included in the test for FREE as this may increase the overall accuracy of the test.

How does the Sibling DNA test work?

The test analyses genetic locations on the DNA strand to create a DNA profile for each test participant. The DNA profiles of the test participants are then compared.

The test is based on the fact that biologically related individuals should have more DNA in common than unrelated individuals. On average the DNA of full siblings will match at more DNA locations than half siblings, and half siblings will match at more DNA locations than unrelated people.

How are the results interpreted for the Sibling DNA Test?

In order to determine the most likely relationship between the individuals tested, complex statistical analysis is carried out on DNA profiles generated. The values from the calculations are used to generate a percentage probability value. For example, if two individuals want to know if they are half or full siblings, the percentage probability will indicate which relationship is most likely to exists.

When should other forms of DNA test be used?

Sibling DNA tests are usually a way of testing the identity of a biological parent, without directly including that alleged parent in the test.

Although Sibling tests can be very accurate and useful DNA tests, they cannot replace the tests that directly test the DNA of a biological parent. For example, if an alleged father is available for testing, then a Paternity DNA test should be used rather than a sibling test.

Inconclusive Results

While these tests can provide accurate results, there is a small chance that the test will yield an INCONCLUSIVE result.

Inconclusive results are not the same as negative results. Inconclusive results mean that the laboratory analysis cannot determine the answer to the question posed by the client.
An INCONCLUSIVE result occurs in approx 22.5% of sibling DNA tests.

Causes of inconclusive results in DNA tests include:

All of the DNA markers that show matches between test participants are very common within the relevant general population. In these circumstances the matches do not provide the required genetic evidence to confirm which biological relationship exists.

There is a low level of DNA matches between the DNA profiles of the participants due to the chance nature of inheritance in families.

Where matches may have originally occurred, mutation has changed the DNA marker and caused mismatches at further locations within the DNA profile.

The Sibling DNA test can be used to answer the following questions:

  • Do we have the same father?
  • Does my brother have a different father?
  • Does my sister have a different father?
  • Do we have the same mother?
  • Do I have a different father?
  • Are we brother and sister?
  • Are we sisters?
  • Do we have the same mother and father?

If any of the parents of the siblings who are being assessed are available for testing, this will aid the analysis and may increase the certainty of the result.

As in a paternity test a DNA profile is produced for each person made up of a number of DNA markers. The DNA profiles of the two people are then compared.

On average full siblings will share more DNA markers than half siblings, and half siblings share more DNA markers than unrelated people. The statistical analysis performed will determine the most likely relationship given the DNA results.

A vast network of local clinics offering Sibling peace of mind DNA Tests...Brothers & Sisters

DNA Clinics provide all Advanced Sibling DNA tests in a clinical setting with one to one consultation and full support through a dedicated case manager for both peace of mind and legal DNA tests for siblings. Call DNA Clinics now to arrange an appointment.

All DNA Clinics nurse's are available for on-site and off-site appointments...District Nurse

The DNA samples for your Sibling test can be taken by a DNA Clinics registered nurse in the comfort of your own home or at another location of your choice. Call today to discuss your DNA test appointment options.

Home DNA test kits are available for peace of mind Sibling DNA tests...Young White Couple

These DNA test kits allow you to take your own DNA samples in the comfort of you own home. Call and order a Home DNA Test Kit today or visit our on-line store to order your FREE DNA Sibling test kit.

Which Sibling DNA Test is right for you?

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What to do Next?

  1. Choose your preferred DNA sample collection service.
  2. For all Sibling DNA tests (except on-line DNA Test Kit orders), call FREE from the UK on 0800 988 7107 to organise your appointment.
  3. Attend the appointment to have your DNA samples collected by a fully trained professional.
  4. Your DNA samples are processed in Crystal Health's accredited laboratory.
  5. You will receive your Sibling DNA test results via your chosen method.

Frequently Asked Questions for Sibling DNA Testing

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