About sibling testing
A siblings DNA test will establish the likelihood of two individuals having the same parents in common. In the absence of an alleged parent, a sibling test is the best option to establish whether the siblings tested share the untested, alleged parent.
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. 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. A sibling test simply seeks to determine whether the individuals tested share one common parent, both common parents or have neither their mother or father in common. In a sibling ship 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.
We strongly suggest including the sample of a known mother to provide stronger results.
Reasons for using a siblings DNA test
- Adopted children, or siblings separated at birth, being reunited but with parents absent;
- Siblings with doubts as to the identity of their biological father;
- Legal cases of inheritance claims by individuals claiming to be children of the deceased.
It is important to identify who will be participating in your DNA test, as this will help the laboratory in selecting the best DNA test for you. Always check if permission is required from legal guardians, when dealing with minors, as this will change from country to country.
PLEASE NOTE: In the event of a possible pre-existing relationship the laboratory would NOT be able to run a sibling test if you believe your cousin could be your sibling. Please contact us to help you find the right test for you.
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 forensic 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.
In cases where siblings are male
If siblings are male and want to discover whether they share the same biological father, we suggest a Y chromosome test. This siblings DNA 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 testing between twins
easyDNA offers siblings DNA testing to verify whether twins are identical or fraternal. Our twins test is extremely accurate and only requires oral swabs to collect the samples of the twins tested. The results for this sibling test are ready in 5-7 working days from receipt of samples at our laboratory.