Sibling DNA Test
Testing: Two alleged siblings
Timeframe: 5-7 working days from receipt of samples at the laboratories
Brothers and sisters can carry out a sibling DNA test to establish whether they share a common biological parent. International Biosciences offers accurate and reliable sibling DNA testing services starting from only $349. This price includes the testing of 2 alleged siblings in an ISO 17025 accredited laboratory and results in 5-7 working days from when we receive your samples at our office.
Note: 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 mother to provide stronger results.
Why do people choose sibling DNA testing?
Brothers and sisters may need to determine whether they really have the same biological father or mother. Our first recommendation to these clients is to suggest a paternity test or a maternity test as directly testing the samples of the alleged parent provides more conclusive results. In cases where obtaining a sample from the mother or father is not possible, we would suggest a sibling test. The results will confirm whether the siblings tested share one biological parent, both biological parents or whether they have no biological parents in common.
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.
Sibling DNA test science
How much DNA do siblings share? On average, siblings will share around 50% of their DNA. But unlike a DNA test between alleged father and child where a conclusive result will need a match at every genetic marker, a sibling test does not require a full match at every marker to be considered conclusive. When the profiles of the alleged siblings are compared in the laboratory, the laboratory analysts will try to determine how much common DNA there is between the individuals tested. This is known as the siblingship index and all siblingship tests assume a prior probability of relationship of 50%. This means that we make the assumption that there is a 50% chance that they are related and a 50% that they are not related. The higher the probability of relationship, the stronger the chances of the two siblings sharing the same biological parent(s); conversely, the lower the probability the more unlikely it is that the siblings share the same biological parent(s).
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.
Collecting your samples & ordering your DNA test
International Biosciences makes sample collection for all its DNA tests as simple as possible. Using our home sample collection kit you can collect your samples using our mouth swabs. We provide you with 4 swabs per person together with instructions, consent forms and a pre-addressed return envelope.
IBDNA offers siblings testing and its entire range of relationship and paternity tests for legal and peace of mind purposes.
Our sibling test for 2 alleged siblings starts from $349. Where possible, we recommend including the sample of the mother or a known parent. This will help us provide you with a more conclusive result.
What test can you suggest if siblings are male?
A Y chromosome testing is the test you need if you are 2 or more males and need to answer the following questions “Do we share the same biological father?” A Y chromosome test is extremely accurate as males that have the same father will also have the same copy of their Y chromosome. It is a more conclusive and reliable test compared to a sibling test because it provides a yes-or-no answer rather than a percentage probability. Read more about Y Chromosome Testing.
What test can you suggest if siblings are female?
X chromosome testing is another accurate DNA test we offer. This test can help 2 or more females know if they have the same biological father. The only important thing to keep in mind is that this test cannot be carried out between females that have the same mother unless they can provide us with the sample of the mother. Even if females have different mothers, we still strongly advise including the mother’s sample. Read more about our X Chromosome Test here.