About siblings DNA testing

A full siblings DNA test is recommended when the individuals taking part in the test are male and female. This type of test establishes the amount of common DNA between the people tested. A sibling test determines whether the individuals tested share one common parent, both common parents or have neither their mother or father in common. It is a test that relies on a statistical probability. Unlike a paternity test however, sibling testing does not need to provide genetic profiles that match at every genetic marker. In a siblings DNA test, we calculate a siblingship index. If the siblingship index is less than 1.00, this indicates non-relatedness. If the siblingship index is greater than 1.00, this indicates that the two tested individuals are more likely to be true full sibling or half siblings. The price of a sibling test is $589 and includes testing two individuals.

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

Important Notes

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.

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

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

Siblings DNA test between brothers

If siblings are male and want to discover whether they share the same biological father, we suggest a different type of siblings DNA test known as a Y chromosome test. This test is extremely accurate. If females wish to establish whether they have a common paternal line they can ask a direct male blood relative to take a Y chromosome test on their behalf.

Siblings DNA test between sisters

If test participants are female and their scope is to find out if they have the same biological father, EasyDNA suggests an X chromosome test. It is important to keep in mind that with X chromosome testing, the sample of the mother will be required in cases where the tested females have the same mother.

Sample collection for siblings DNA testing

Samples needed for a siblings DNA test can be collected using oral swabs. We provide you with a home kit following your purchase which will contain 4 colour coded swabs per person. Swabs need to be rubbed inside the mouth and under the tongue for around ten seconds and then be left to dry. Kits will also contain instructions and consent forms. Clients will needs to ensure to fill in the consent forms before returning their samples back to us. Siblings DNA results are ready in 7-10 working days following the receipt of samples at the laboratory.

Brothers and sisters with the same mother or maternal line

Brothers and/or sisters who wish to know if they have the same maternal line test their mitochondrial DNA. This is a special type of DNA that is inherited by both male and female offspring from their mother. However, it is only females that can pass their MtDNA to their children. If two or more individuals have any common, biological maternal ancestor then they will also have the same MtDNA profile.The only drawback with MtDNA testing is that the test result will only tell you whether you share a common maternal ancestor or not – it will not tell you which ancestor you have in common (that is, it will not confirm you have the same mother, a common aunt, a grandmother, great grand mother and so forth). For  more about MtDNA click here.

If you want to know with 100% accuracy whether you have the same mother you would need a maternity test. Contact us for more information about  our siblings DNA test or any other test.

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