Sibling Testing

DNA Test for Siblings – 44 Markers

Full Sibling DNA Test/Half Sibling DNA Test

full sibling dna testing, half sibling DNA testing

How accurate is a sibling DNA test?

Our 44 marker sibling DNA test  is guaranteed to be the most accurate test available

A sibling DNA test determines the statistical probability that two or more persons are or are not related as full or half brothers and/or full or half sisters. A sibling test is normally performed when a standard paternity test is not possible making this test the best way of establishing paternity through the alleged father’s suspected children to see whether they are biologically related to each other.

In the sibling test, the two or more alleged siblings (either half siblings or full siblings) that are being tested don’t have to share DNA in common at all the genetic markers being examined, unlike a father and child do. This means that the outcome of a sibling DNA test relies solely on statistics.

When  we perform a sibling DNA case study, we are trying to determine if it is more likely that they share two common parents, one common parent or no common parents which would make them either full siblings, half siblings, or unrelated. We can perform a sibling DNA test with two possible half siblings in most cases without the DNA of one or both of the mothers due to the fact that we test 44 genetic markers for a more accurate result with fewer people testing. Our 44 marker testing is over 10,000 more accurate than the standard test, based on statistical reliability.

most accurate sibling dna test accuracy

Unlike a DNA paternity test which should always provide a conclusive result, sibling DNA testing is a little different. When a sibling DNA test is conducted, the laboratory will determine the genetic profile of  each of the alleged siblings. Based on the type of genetic material exhibited by each person, a sibship index is determined. If the siblingship index is less than 1.00, this indicates non-relatedness. If the sibling 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 sibling index, the greater the likelihood that the two individuals are true biological relatives. This index is translated in a probability percentage for easier understanding. A probability percentage of 80% or greater is a conclusive result.


DNA Test 

Lab Processing Time

Cost Per Test

2 Siblings (Full or Half Sibling) 2 business days $199 »
3 Siblings (Full or Half Sibling) 2 business days $299 »
4 Siblings (Full or Half Sibling) 2 business days $399 »
5 Siblings (Full or Half Sibling) 2 business days $499 »



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Home/Private Sibling DNA Testing

Bio-Gene DNA Testing will only perform home Sibling tests using our 44 genetic marker comparison test. Our full sibling and half sibling DNA testexamines a much higher number of markers than the industry standard of 16 markers, and the reason for this is that we have found lower marker tests often require many additional tested parties (at a higher cost to you and it is often more difficult to get additional potential siblings/family members to cooperate) and the test finding can still come back with inconclusive results  in an alarming number of instances. Our 44 marker sibling test helps eliminate these problems in almost every case.

How a Home Sibling DNA Test is Performed

The most accurate method of obtaining your DNA is to use a buccal swab, which is very similar to a “Q-tip” cotton swab. The swabs are rubbed on the inner 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 swab sample. Because of this we are often able to test alternative samples. The sample should have been stored in a paper envelope or breathable environment without extreme temperature changes for the best results in extracting the DNA. The sample should not have been stored in a plastic bag for any extended period of time. If you have questions, please call one of our Genetic Consultants at 1-844-BIO-GENE (246-4363) to discuss your particular sample prior to ordering a test. Some of the alternative samples that can usually be tested include:

Amniotic Fluid Cups / Bottles Feminine Hygiene Razors
Bandaid (Used) Dental Floss Fingernails Tissue
Chewing Gum Earwax Hair (With Root) Tooth-brush
Cigarette Butt Electric Razor Hat (Well Worn) Toothpick
Condom (Used) Envelope / Stamp Pacifier Underwear

Disclaimer: Although the items listed are examples of excellent alternative DNA samples, we cannot guarantee there will be a usable DNA sample on a non-standard item.

Accurate Sibling Testing

Please take a moment to review some of our case studies below. The following information helps to understand the difference between 16 marker test (used by most testing companies) results and our 44 marker test results.The benefits of testing more markers can be found in the results from cases in each real life scenario. If you have any questions, be sure to consult with a Genetic Consultant at 1-844-BIO-GENE (246-4363).

Case 1

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 DNA Testing has chosen to only perform tests with more DNA markers, or data points. When we examined these sisters using our 44 marker test, we found the probability to be 97.15% that they were full siblings, which was already known to be true.

sibling DNA test results


Case 2

The two siblings in this case were adults whose parents were deceased. They had different mothers and wanted to know if they were half siblings. They had always had a suspicion that they might not share the same father and turned to DNA testing to put their minds at ease. The results of the 16 marker test found that the probability of being unrelated was only 78.83% and it seemed that their suspicion might be correct. However, the percentage was not high enough to conclusively say they were not related. When the 44 marker test was applied to their case, it was found that the probability they did not share the same father was 98.66%.

sibling DNA


Case 3

In this sibling case, the purpose of testing was to determine if the two possible 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 44 marker sibling test, the results indicated that the probability of being unrelated increased to 99.96%.

how accurate is a sibling dna test


Case 4

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 44 maker sibling test was used, they were found to more likely be half siblings at 99.77%.

sibling test


The conclusion that can be drawn from these cases is that a 16 marker DNA Test will not be sufficient, in most cases, if a conclusive result is desired.


How to Order a Sibling DNA Test

How does a sibling DNA test work graphic



To order your Sibling DNA Home Test Kit, please complete the order form by clicking on the ORDER NOW button.  Our prices can be found by selecting the test of your choice, the number of people testing, and your shipping preferences when providing the information that is relevant to your particular case.


how to order a sibling DNA test


When ordering a sibling test you may choose to order a testing kit from Bio-Gene DNA Testing or build your own kit. This may be especially helpful is you are using alternative samples, or do not wish to wait for the kit to arrive to your location due to time constraints. If you chose to use a Bio-Gene DNA test kit, you will choose the shipping option that is right for you. Once your kit is mailed, you will be provided a tracking number by the USPS to be able to determine when it will arrive, usually within 2 business days.

Make Your Own Sibling DNA Kit

If you choose to use your own kit, yhome sibling dna test kitou will choose the “make my own kit” option on the order form, and within 4 hours of the receipt of your order (during regular business hours) you will receive by e-mail a submission form, a unique case ID number (we cannot process any DNA samples without this number), instructions on how to collect the samples, and our lab’s address to send your samples to for immediate processing.

To learn about using your own DNA testing kit, please click HERE. We strongly encourage the use of your DNA testing kit for those needing testing who live outside of the United States.

What the DNA testing results look like

Due to performing our high marker tests, Bio-Gene DNA Testing is able to deliver results that show conclusive results in almost every single case we handle. The sample results below show how the genetic code is listed , and how the results are written.

We show two conclusions in each of our reports. The first conclusion assumes that the participants have one common parent (usually a mother) in common, and gives the probability of whether they are full siblings or not. This testing is performed on all sibling cases, even when there is already knowledge that at least one parent is not biologically related. If the indication shows the two (or more) individuals are not full siblings, then this gives a basis  to then perform testing for a half-sibling relationship.

The second conclusion assumes that the participants do not share at least one common parent and reports the probability of whether they are half siblings or unrelated. We are therefore able to obtain a result that will show you have a very high probability of being sibling (the highest possible in testing is 99.9%) or that you are not related.

The testing reports are written in a way this is easy to understand, and we always provide a free consultation on testing results if needed.

In the first case below we were able to determine beyond a reasonable doubt that the two alleged siblings were full biological siblings. The second case example below indicate there is no biological relationship between the two suspected siblings.

While these are only examples, and each testing result will vary depending on the genetic profile of each person being tested, they are representative of testing results that will be issued upon completion of your case.

full sibling dna test results

half sibling dna test results


If you have questions you can e-mail us at, or you may call one of our Genetic Consultants at 1-844-BIO-GENE (246-4363) to discuss your case confidentially.

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