Sibling DNA test

Can 23andme find half siblings? Consider this curious story that was published in the Daily Mail about 23andme siblings. There was a police officer, Sgt. Dave Stull, living in Florida who had been adopted as a baby. After the deaths of his adoptive parents, he had a desire to learn more about his biological parents. He decided to use the popular DNA consumer testing company, 23andMe. Through the process, he discovered he has a half brother in Florida who was also a cop! This story is an answer to whether 23andme can find siblings and due to stories like this, these ancestry and sibling DNA tests have gotten more popular.

A sibling DNA test can prove if allegedly related siblings are full siblings, half siblings or unrelated and can also help to prove or disprove paternity or maternity indirectly. This DNA test is the best choice when either the alleged father or mother is unavailable or unwilling for the test. There are many of these DNA testing companies that provide these services but how accurate are they?

How accurate is a Sibling DNA test?

A sibling DNA test is simply a means of verifying the true nature of the relationship between the offspring of sets of parents. The science behind the test compares genetic material that is passed down from parents to determine the likelihood that two people are biologically related. Therefore the tests usually have 100% accuracy because of the closeness of such relationships.  

Consider again the 23andme siblings, sergeant Dave discovered that there was a list of more than 1,200 potential relatives. This is because the 23andMe database compares the similarities in their DNA which shows that they might be siblings. This happened without the need for parents or parental DNA, only the half-sibling’s DNA was needed.  

The closest and most likely match that topped the list of 1,200 potential relatives was officer Eric Reynolds who he didn’t know at the time. Eric had a similar jawline but a different eye color. Dave emailed Eric that they were half brothers but was not sure of how valid the test would be. They eventually got acquainted and confirmed that they were related confirming the 23andme sibling accuracy

If you search for sibling DNA tests on amazon, you will find a lot of mixed reviews but the results depend on the DNA testing company and the minor discrepancies that might be in each individual sibling DNA test kit as with any medical test. 

Though it is difficult to issue an accurate fraction of how much DNA is shared between siblings or even twins, it is a fact that relatives share DNA and there is little margin for error especially when questionable results are retested. So whether the question is do brothers and sisters share the same DNA or do biological siblings have the same DNA, the simple answer is yes, they share comparable DNA.

Can you find lost siblings with a DNA test?

There are tons of stories about reunited siblings such as the 23andme siblings in Florida. While this is possible for anyone, it is very unlikely to find lost siblings this way because of probability. This is because the odds of finding a sibling this way depends on whether they might be in the DNA testing companies’ database or not. Some companies like have a huge database of over 5 million people. So if you want to find a long lost sibling perhaps ordering a test with a company that has a large database might be the best choice. 

Another option would be to try the family tree builders which are offered by companies such as Ancestry, MyHeritage and others. These enable you to discover links in your family tree and find new relatives and siblings and have proven very useful. 

Can a DNA test between siblings show how much genetic material they share?

DNA test between siblings that have the same biological parents share an estimated 50% of their DNA. This percentage may vary a bit, in the case of identical twins, their DNA is close to 100%. Full siblings have both parents in common while half-siblings have only one parent in common, either the biological father or mother. 

Full siblings are first-degree relatives tend to share 50% of the genes they inherited from their parents. While half-siblings who are second-degree relatives share less than 50% of their genes that maybe overlapping and first cousins share only about 25% of their genes.  However, The best sibling DNA tests determine the likelihood of siblingship by checking about 700000 markers in found in the DNA samples.

Will siblings have the same DNA ancestry?

It makes sense that most people believe that the ancestry in DNA siblings should be the same since they get half of their DNA from their mom and half of their DNA from their dad but this is not the case. DNA testing companies like and 23andMe have videos and articles explaining this to their customers.

It is very likely for two siblings to have some remarkable differences in their ancestry at the DNA level. In fact, the siblings sharing similar DNA can have different ancestry despite their background. This has inspired many YouTube videos about ancestry in DNA siblings. In such videos siblings record the entire process of checking their ancestry and compare results at the end. 

It is interesting to find out that one sibling might claim to be culturally 1/4th French but find out that their other siblings might have a higher percentage of French DNA or even none at all. While this brings much humor and excitement there is a true genetic reason for this.

However, there being a family mismatch doesn’t mean one sibling was adopted or that there is some family secret. The is a genetic reshuffling happens during fertilization when the sperm and egg combine and this process is unique for everyone and affects large sections of DNA. In order to form a complete genetic package, 23 chromosomes from each parent is obtained to form unique individual humans. This is why siblings don’t look 100% alike. 

This variation is also due to how DNA is passed down from generation to generation. A process called genetic recombination mixes up the same DNA pools so that each sibling has a different set of DNA despite it coming from the same source, the previous generation. So DNA isn’t passed on in entire blocks, it is passed on through random shuffling and mixing. This is why siblings who share the same parentage can have difference in their DNA ancestry. 

Another reason could also be that, the databases of certain companies might not be large enough and focus mainly on North America and Europe. Therefore, because these tests that determine ancestry by comparing new DNA tests to databases of known samples, people from other places in the world, could have DNA results that could be less specific. 

DNA tests such as Mitochondrial DNA tests and Y chromosome test can be more specific regarding ancestry because the way it is passed down is different and is not really affected by DNA recombination. Read more about the Y chromosome DNA tests.

What companies provide the cheapest sibling DNA tests?

  1. My Heritage offers a sibling DNA test for $69 and the results will be received in 4 weeks. This test involves a cheek swab during the sample collection process. They have a database of 1 million people and building. When 2 people want to determine whether they are siblings, they use MyHeritage’s DNA service to see if they will be a match. MyHeritage claims to have 100% accuracy for a sibling relationship while having an estimated 93% accuracy for distant relatives like fourth cousins. 
  2. LivingDNA has a sibling DNA test for $89 and the results will be sent in 4-6 weeks. This also involves a cheek swab during the sample collection process. The results from this DNA test show the fatherline, motherline and distant relatives too. Anyone who takes their DNA test is made aware if they have matched with someone in their database. 
  3. Vitagene is backed by Stanford University and Berkeley.  Vitagene offers an indepth look at a person’s DNA makeup through genotype testing. Potential siblings involved can compare their results. A vitagene test kit costs $89. The results will be received in 4 to 6 weeks
  4. Although 23andME does not offer sibling tests in their product listing. However, the company offers a DNA test that is very comprehensive and enables you to find a match if both you and your potential siblings take the test and enter their database. You will be contacted if you match your potential sibling. Their test cost $99, involve taking a saliva sample and the results are gotten within 6 to 8 weeks. 
  5. Ancestry is a world leader in DNA testing and has a database of over 5 million people. Their reviews claim that they can prove sibling relationships at almost 100% accuracy. Their preferred sample is saliva and the test takes 6 to 8 weeks to produce results. They compare your sample with samples in their large database and they give you a ranked list of potential DNA matches who could be a family member. 

How to order an at home sibling dna test

  • Buy the kit: Order your sibling DNA test online from one of the DNA testing companies. The test kit will be delivered to you. 
  • Register the kit: Go online to the website of the company and register your kit’s barcode.
  • Collect the sample: Follow the detailed instructions on how to use the swabs or test vials in the collection kit to gather the sample or whether they require a blood or hair sample. Some require you to provide saliva on a control line. Make sure to take the following precautions, don’t eat or drink for up to 45 minutes before giving the saliva sample. Also avoid brushing your teeth beforehand. These step will ensure the DNA you provide will remain undamaged. Place the sample back in the kit carefully and send it to the address given in the instructions. Follow these same collection instructions for either brother or sister or anyone else involved in the test.
  • Sample analysis: You will receive an email when your samples arrive at the laboratory. The scientists at the company will extract and examine the DNA to analyze the genes. This will take about 4 to 8 weeks to process depending on the country.
  • Receive the report:  Many companies send you a unique personalized report after they have processed your DNA samples. This usually comes in an email or uploaded to your registered account.


Legal sibling dna testing

Legal sibling DNA testing is used to verify whether two siblings share a parent as part of a court judgment or other legal procedure. When other methods like paternity or maternity DNA tests which would be more direct but not available, these sibling DNA tests can be more conducive. These tests can be carried out in a hospital, medical office, laboratory or clinic. Legality requires that the place of DNA sample collection has to be unbiased.

There is usually one of 3 outcomes: Half-sibling, full-siblings or unrelated. These legal brother sister DNA tests can be ordered by the law court for one of the following reasons: 

  • Wills 
  • Tax Forms
  • Immigration
  • Court Orders 
  • Adoption cases 
  • Child custody cases 
  • Child support issues 

Legal sibling DNA testing can be expensive. Therefore it is better to obtain DNA from all 3 parties involved, namely the potential siblings and the known parent. This is to prevent inconclusive sibling DNA test outcomes that are possible without the DNA of the parent whose is known. However, a DNA test to determine sibling status can be done if the parent’s DNA is unavailable. A court-admissible sibling DNA test is usually more meticulous to ensure the accuracy of the test.

Validity Genetics offers Legal sibling DNA testing for $299 and within their kit are buccal collection swabs per person, sample envelopes per person, a consent form and a prepaid return label to their laboratory. They claim to have a turnaround time of 2 to 3 business days, and they are also an ISO 17025/9001 certified laboratory and they guarantee accuracy. They say their tests are fully admissible in court across the United States and Canada. 

Steps for a Legal Sibling DNA testing 

  • Order your legal Sibling test online:  Order your DNA test like you would any other product online.  Follow the instructions. The difference here is that for any DNA test to be considered Court Admissible it must be shipped to and handled only by an uninterested and unrelated 3rd party. This 3rd party will also be responsible for sample collection, identity verification of those involved. The third party can be anyone, such as medical officer, a doctor, a lawyer, a notary, nurse, family friend or pastor.  Register the kit: Go online to the website of the company and register your kit’s barcode.
  • Collect the sample: Follow the detailed instructions. Make sure to have a recognized government ID and for child they should have a valid birth certificate. These should be photocopied or scanned by the sample collector. The required documents will be sent to the DNA testing company, along with the needed paperwork. 
  • Receiving legal DNA results: The DNA test will be processed in a safe and secure lab. The test is usually completed in a few DNAs and the result will be cross-checked before sending you the results. 

Sibling DNA test options

Based on the parental relationship, there are the following tests: 

  • Full sibling vs Half-sibling DNA test
    • This type of full sibling DNA test is used to investigate the chance of whether two children of the same biological mother might have the same biological father or not. Therefore in this kind of test, the DNA of the biological mother is needed so that the accuracy of the test would be undoubted thus preventing an inconclusive sibling DNA test. These tests are usually ordered in cases where there are 2 fathers and the parentage of the children is in question and an at-home sibling DNA tests surely differentiate between full siblings and half-siblings.  
  • Full sibling vs Unrelated DNA test
    • This is test is common in immigration cases such as when a U.S. citizen is supporting a brother or sister who is applying for an immigrant visa to the U.S the test can prove their relationship. In this DNA test between brothers and sisters, the DNA is compared with each other to show the likelihood of them having the same parents and thus their relationship.  
  • Half sibling vs Unrelated DNA test
    • This half-sibling dna test is done to determine the likelihood that two different women had a child with the same man or not. So having a sample from both biological mothers will improve the test results. This often happens frequently in disputes about parentage and inheritance.