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Sibling DNA Test

“Excellent service we decided to find out once and for all if our twin boys were in fact identical (which after taking your test we now know that they are!). It was easy to do and the results came back quickly. Thank you.”
Alison- 25th March 2017
★ ★ ★ ★ ★

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.

Order now €269

Sibling DNA Test

Price: €269
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 €269. 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.

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 our laboratory, our 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 €269. 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 at an additional cost.


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.

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