This type of DNA test determines the likelihood statistical probability that two or more persons are related as brothers and/or sisters. A sibling test is normally done when a paternity test is not an option and thus the only means of establishing paternity is by testing the alleged father’s suspected children to see whether they are related to each other.
Unlike a DNA paternity test which will always provide a conclusive result, siblingship DNA tests are different. When a siblingship DNA test is conducted, the laboratory will determine the genetic profile of the alleged relatives. Based on the type of genetic material exhibited by each person, a siblingship index is determined. 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 higher the value of the siblingship index, the greater the likelihood that the two individuals are true biological relatives.
Private Home Sibling DNA Testing
Bio-Gene will only perform home Sibling tests using our 41 marker test. Our sibling DNA test examines a much higher number of markers than the industry standard, and the reason for this is that we have found lower marker tests often require additional tested parties (higher cost to you and often more difficult to get additional potential siblings/family members to cooperate) and can still come back with inconclusive results many times. Our goal is to always do what is in your best interest. To learn more about this test, click here.
The most accurate method of testing is to use a buccal swab, which is similar to a “Q-tip”, which has been rubbed on the cheeks of the mouth of those being tested. We provide these with our collection kits. However, sometimes it is not possible to obtain a buccal sample. We are able to test alternative samples, normally at no extra cost. The sample should be stored in a paper envelope or breathable environment for best results. The sample should not have been stored in a plastic bag at any time. If you have questions, please call one of our Certified DNA Examiners to discuss your particular sample prior to ordering a test. When using an alternate sample you do run the risk of the non-standard sample failing for unexplained reasons.
Some of the alternative samples that can usually be tested include:
- Blood sample
- Bandaid (Used)
- Feminine Hygiene
- Ear wax
- Chewed gum
- Tissue (Used)
- Hair (8-10 strands with the roots attached)
Please take a moment to review some of our case studies. The benefits of testing more markers can be found in the multiple cases in each scenario. If you have any questions, be sure to consult with a Case Manager at 1-888-391-5256.
Bio-Gene’s 41 Marker Sibling DNA Test
The following information helps to understand the difference between 16 marker test (used by most testing companies) results and our 41 marker test results.
This case illustrates why testing more markers will produce more accurate results. Samples were voluntarily collected from our lab employees and their families and then sibling comparisons were performed. One case stood out because two sisters, that were known to be FULL siblings, were being reported as having a 95.39% probability they were half siblings when using the industry standard 16 marker test. Why did the 16 marker test produce a result that was false? Sibling DNA testing is based on statistics and, with such a limited number of data points, in the case only 16 markers, the statistics were wrong. In order to lower the possibility of this happening, Bio-Gene has chosen to only perform tests with more DNA markers, or data points. When we examined these sisters using our 41 marker test, we found the probability to be 97.15% that they were full siblings, which was already known to be true.
In this sibling case, the purpose of testing was to determine if the two possbile siblings were half siblings or unrelated. In this case, both mothers also contributed samples. It was reported that the probability they did not share the same father was 71.67% after testing all four people with 16 markers. A percentage this low cannot be trusted as it is not a conclusive result. After testing with the 41 marker sibling test, the results indicated that the probabilty of being unrelated increased to 99.96%.
Two men had the same mother and the standard 16 marker sibling test was performed. It was found that the probability of being half siblings was only 75.23%, which is an inconclusive result. When the 41 maker sibling test was used, they were found to more likely half siblings at 99.77%.
The conclusions that can be drawn from these cases is that 16 markers will not be enough to test in most cases, if a conclusive result is desired.
Understanding The Sibling DNA Testing Results
A Sibling test will help to provide you with an indication of whether you are more likely to be a full sibling, half sibling or not the true biological sibling of the other tested individual.
Remember, on average, full siblings have 50% of their DNA in common. Half-sibling DNA testing involves two or more individuals who potentially share only one biological parent. Half siblings generally have 25% of their DNA in common.
Sometimes it can seem that getting an answer that should be easy to obtain and understand instead is turning into a very complicated and confusing issue. Bio-Gene does not believe it should take a genetics degree to understand your test results. That is one reason we only perform 41 marker testing for siblings and family relationship testing. In 99.99% of the cases we handle we are able to obtain a result that our clients rely on as conclusive as to a biological relationship.
Because siblings don’t always share common alleles at each location, results from a Sibling DNA Test will determine how likely the two individuals are fully related, half related, or unrelated. In most cases, the two siblings know that they share the same mother and want to know if they share the same father.
When a sibling test result is completed, it is easy to ready. Below is an example of what might be expected.
As you can see, we write two conclusions in our reports. The first conclusion assumes that the participants have the same mother, or one common parent, and gives the probability of whether they are full siblings or half siblings. The second conclusion assumes that the participants have different mothers and reports the probability of whether they are half siblings or unrelated. In the case above, the two people testing did have the same mother and this test result showed that they also shared the same biological father. If they had not shared a common mother, Conclusion 2 would have indicated that they still shared a biological father, making them half siblings. When there is no biological relationship it is called an exclusion. The testing report will look the same, but the conclusion will show the probability of relationship to low to be probable.
To order your Sibling DNA testing kit, please complete the order form below and you will be taken to our secure server. We offer a single pay option (at a discounted price) as well as a payment plan, because we understand that every case is unique. Our prices can be found by selecting the test of your choice, the number of people testing, and your payment preferences when providing the information that is relevant to your particular case.
If you have questions you can e-mail us at siblings [at] biogenednatesting.com, or you may call one of our Case Managers at 1-888-391-5256 to discuss your case confidentially.