About sibling testing

Due to New York State Department of Health regulations, we cannot offer any peace of mind paternity or relationship tests to New York residents. However, we can offer legal paternity and relationship tests in New York. Contact us or click here for more information.

siblings DNA test is suitable for when two or more siblings want to verify whether they are genetically related or not. It can also be used to determine if they are half siblings, full siblings or whether they are not related at all. Sibling testing is only carried out in cases where the people taking part in the test are brothers and sisters – in other words both male and female test participants are involved in the same test.

Siblings who carry out this test want to know whether they share the same biological father. However, a sibling test will never provide a result that is as accurate as a paternity test. The cost of a sibling test is $299.

We strongly suggest including the sample of a known mother to provide stronger results.

Your siblings DNA test results

Siblingship test results are based on statistical calculations which will provide what is called a siblingship index. How accurate a siblingship test result will be is hard to predict as it very much depends on how much common genetic material the individuals share and whether or not they have included the sample of the mother. Siblings share around half (50%) of their DNA. A sibling test will establish what is known as a siblingship index.

Test results are intended to provide a statistical likelihood that gives evidence to support the tested relationship in question. Providing additional parties to be tested (for example, a known parent’s sample) or performing direct relationship testing may provide additional evidence.

In the case of all relationship testing, we recommended that a known parent (normally the Mother) is included in the test to strengthen the result.

Siblings DNA Testing: Collecting samples

Samples for siblings DNA testing can be collected with EasyDNA’s own sample collection kit which will be sent to you once we have confirmed your order. Compact, discrete and easy to use, our sample collection kit will enable you to collect the DNA samples we need in just a few easy steps. Kits contain 4 swabs per person, consent forms and instructions. To learn more about the sample collection procedure, click here.

Note: We can only guarantee standard result turnaround time when siblings DNA testing takes place solely using oral swab samples. Using a discreet sample for your test may lead to an increase in turnaround time.

If Siblings are female

If the siblings being tested are females and want to know if they share the same biological father they will require an X chromosome test. Including the mother’s samples is necessary for the test if the females share the same mother. For more information about this test, visit our X chromosome testing page.

If Siblings are males

Rather than a siblings DNA test, a Y chromosome test can be carried out if the siblings being tested are all male and wish to discover whether they have the same birth father or different birth fathers. This test determines male lineage. Visit our Y chromosome testing page for more information on this test.

An MtDNA test can be carried out if siblings are either sex and wish to determine maternal lineage. Visit our mtDNA testing page for more details on this type of test.7

Common Cases for DNA Sibling Testing

The most common use for this test is to determine the likelihood of individuals having the same parents in common. In situations where one or both parents are unavailable or unwilling to be tested, the next option is to analyse DNA between siblings and make direct comparisons.

There are many different reasons for siblings resorting to siblings DNA testing to prove a biological relationship. In some cases, siblings have been separated from young, and find their alleged siblings later in life, often after parents are deceased. Sometimes a sibling will have doubts as to who their real father is. They will feel sure they share the same mother but have concerns over their biological father.  A sibling test will clarify whether siblings are full or half, possibly eliminating any doubts over paternity. Last but not least, during inheritance disputes or claims, it can often be of importance for siblings to prove their relationship and whether they are full or half siblings can greatly affect the outcome of a will.

Before embarking on a siblings DNA test it is important to identify who is available for testing as this will assist the DNA laboratory to decide which test is most applicable to your case. There can also be various stages of testing with additional people included in the testing if the first results do not yield a satisfactory result. Also in the case of minors permission from the legal guardians or parents may be required.


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