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Sibling DNA Tests

Sibling DNA tests offer a way to unlock answers and potentially create connections that last a lifetime. Let’s explore the types of sibling tests, their uses, and how the process works.

What is a Sibling DNA Test?

  • Sibling DNA tests examine shared genetic markers between two or more individuals. They reveal with accuracy whether you share both parents (full siblings), one parent (half-siblings), or have no sibling connection.
  • These tests are scientifically accurate tools for verifying and uncovering hidden family relationships. They are often used to determine if a family rumor or ancestry report is correct. We have found over the years that ancestry report information about possible siblings have been wrong about fifty-percent of the time.

Why Someone May Want To Do A Sibling DNA Test?

There are many uses for a sibling test to be done. Our home sibling test kits and legal sibling tests provide the exact same result as they are processed the same way. However, only legal DNA testing can be used for anything that requires legal proof of the relationship.

  • Establishing Paternity: Determining the biological father of a child for personal knowledge or for legal purposes such as child support, custody, and parenting rights.
  • Helping Adoptees Reunite With Birth Family: Siblingship tests are often used by adoptees wanting to connect with biological siblings or learn more about their ancestry.
  • Resolving Inheritance Issues: For inheritance and probate claims, a sibling DNA test can solidify the claim of a rightful beneficiary.
  • Claiming Social Security Benefits: Providing evidence of familial relationships to qualify for social security benefits or survivor benefits.
  • Changing The Name On A Birth Certificate: Verifying biological relationships as part of name change proceedings, especially when there are disputes or uncertainties regarding parentage.
  • Surrogacy/IVF confirmation: Confirming biological parentage in cases of surrogacy arrangements, and IVF treatments, to ensure legal rights and responsibilities were appropriately completed.
  • Settling Insurance Claims: Providing evidence of biological relationships for insurance claims, particularly in cases where beneficiaries need to be identified or contested.
  • Fulfilling Court Orders: Compliance with court orders or legal requirements for sibling DNA testing as part of legal proceedings, including criminal investigations or court-mandated paternity tests.
  • Proving Relationships For I.R.S. Tax Filings: The federal government is increasingly requiring proof of a biological relationship to verify dependent status. In some cases this will require a DNA sibling test result.

Different DNA Tests That Can Prove Siblingship

  • Full vs. Half Sibling: Determines if two people share one or both biological parents. If both of those testing as siblings have the same mother, then this full sibling test should done.
  • Half-Sibling vs. No Sibling Relationship: This DNA test is done when the participants know that they have different mothers and want to determine if they have the same biological father.
  • Grandparent DNA Test: If it is not possible to do a full siblings test, you may want to consider grandparent testing as an option. Here we use the suspected parent’s mother or father instead of the parent. This type of testing can be done with one grandparent and one child. If the results confirm a grandparent-grandchild relationship, it can be determined that the biological son of the grandparent is the father and siblingship can be verified.
  • Avuncular Testing: You can also uses an aunt or uncle’s DNA instead of a suspected parent, if the sibling is not available. The aunt or uncle must be a full brother or sister of the suspected father. In the same way that a grandparent test can confirm paternity, the results of an avuncular test can also confirm the relationship.

Choosing The Right DNA Test: At-Home vs. Legal

At-Home: Convenient and private. Simple collection kits let you take DNA samples at home. These are great for satisfying personal curiosity but results aren’t usable in court. Our home DNA test kits will also allow the testing of items that are not mouth swabs in the event a more discreet testing is desired. Items that can be tested that are not mouth swabs can be found by going to Alternative DNA Samples.

Legal: Court-admissible DNA results for official matters like inheritance, immigration, or child custody. Samples are collected with strict ‘chain-of-custody’ procedures, and labs follow legal-grade testing protocols. If you want to learn about what’s involved in legal test, please click on Legal Sibling Test.

How Accurate Is A Sibling DNA Test

Our sibling DNA tests offer 100% accurate insights into sibling relationships. While not a “yes” or “no” like direct paternity testing, we provide you an accurate answer every time. AABB, the gold standard in DNA lab accreditation, and one of the accreditations that our lab holds, states that anything over 91% verifies the relationship with certainty. A common misconceptions is that accuracy and probability are the same, when they are not. The probability we provide is 100% accurate.

How Does a Sibling Test Work?

Everyone inherits roughly 50% of their DNA from each parent. Full siblings share about 50% of the same DNA.

Half-siblings will share about 25% of the same DNA. When we are testing for this relationship we are focused on the DNA samples to determine if they share sufficient DNA to verify the relationship.

Our laboratory analyzes 24 specific DNA segments to see how much you share with another potential sibling. If we cannot obtain a strong enough finding, we will examine additional DNA markers, at no additional cost, for the strongest findings. When possible (not required), we encourage a mother’s participation to eliminate her DNA from the sibling(s) she is the biological parent of. This allows for a review of only the suspected father’s DNA.

Read more about how we process your DNA and determine your results?

Here’s a step-by-step breakdown of how DNA, the unique molecule that encodes your identity, is extracted from a simple cheek swab and used to calculate the probability of a sibling relationship.

DNA extraction and profiling is a complex process with many variations depending on the specific technique used. This is a simplified explanation of the statistical calculations involved in relationship testing.

  • Step 1: The Buccal Swab Collection: The journey begins with collecting cells from the inside of your cheek. These cells hold the key to your DNA code. A long handled swab, called a “buccal” swab, is gently rubbed against the inner cheek for a short time. This painless process collects a sample of cells containing your DNA.
  • Step 2: Opening the Cells: Imagine the collected cells as tiny balloons containing your DNA instructions. Our specially trained lab technicians need to access these instructions, so they use a special solution with enzymes. These enzymes act like scissors, carefully breaking down the cell walls and releasing the DNA from its secure storage within the balloons.
  • Step 3: Isolating the DNA: Now that the cell walls are broken, the DNA is floating around with other cellular debris. Technicians use chemicals that specifically attract DNA, like tiny magnets. These chemicals bind only to the DNA, separating it from the rest of the cellular material.
  • Step 4: Purifying the DNA: After grabbing the DNA, we then wash away the leftover cell parts and the chemicals used earlier. This leaves behind a purified sample of DNA, similar to having a single strand of spaghetti after cleaning the kitchen after a large meal.
  • Step 5: Making Millions of Copies of the DNA: DNA is very small, so we need to make millions of copies for further analysis. Our technicians use a machine called a thermal cycler, which acts like a high-tech photocopier specifically for DNA. This process, called Polymerase Chain Reaction (PCR), creates enough DNA for the next step.
  • Step 6: Building Your DNA Fingerprint: Each person’s DNA is unique, containing specific repetitive sequences called Short Tandem Repeats (STRs). These STRs vary in length between individuals, creating a personalized pattern. In the lab a technique called gel electrophoresis is used to separate the copied DNA fragments based on their size. Picture separating different colored beads by size! This separation creates a unique pattern of bands on a gel, similar to a fingerprint, but for your DNA – this is your DNA profile.
  • Step 7: Comparing Profiles and Sibling Probability: Now comes the exciting part – comparing DNA profiles! Let’s say you want to determine the probability of someone being your half-sibling. The next step is to compare the STR band patterns of both individuals’ DNA profiles. Half-siblings will share about 25% of their STR alleles (versions) due to inheriting DNA from only one parent.
  • Finally: Here’s where statistics come in. To calculate the probability of a random match between two profiles, we use a formula called the Monopolymorphic Locus Exclusion Chance (MLEC). This formula considers the frequency of each non-matching STR allele in the general population. A higher allele frequency leads to a higher chance of a random match.
  • The MLEC formula multiplies the individual allele frequencies at each analyzed STR locus where the profiles differ. For half-siblings, with mismatched alleles at some loci, the MLEC will provide a probability between 0 (certain not related) and 1 (certain to be related). The closer the MLEC is to 1, the higher the probability of a random match, and conversely, the closer to 0, the lower the chance of a random match and the stronger the possibility of a half-sibling relationship.

Example: For this example, let’s imagine we are analyzing 10 STR loci (we actually use 24 in our standard test, and up to 40+ if extended testing is necessary). We now find mismatches at 3 loci in the profiles being compared. If each mismatched allele has a frequency of 0.2 (20% occurrence in the population), the MLEC would be: MLEC = (0.2 x 0.2 x 0.2) (multiplied 3 times) = 0.008. This calculation results in a very low MLEC, signifying a very low probability of a random match between these two individuals. While this doesn’t definitively prove a half-sibling relationship, it suggests a much higher likelihood than if the MLEC were closer to 1.

By analyzing multiple STR loci and calculating the MLEC, laboratory Ph.D.’s can assess the probability of a half-sibling relationship based on DNA profile comparisons. This powerful tool helps us understand our genetic connections and family history!

How Much Does Sibling Test Cost?

Journey Genetic Testing makes it easy for you to get the DNA testing you need. You can order directly online 24/7/365 in a secure and safe online order form, or you can speak to one of our Genetic Consultants at 1-855-362-5224.

  • Home Sibling DNA Test Kit – $129. Includes two participants to determine their sibling relationship, and a mother’s DNA is included at no additional cost. Kits are shipped USPS Priority with a prepaid overnight return label. Results are ready in two business days after we get the DNA samples.
  • Legal Sibling Test – $299. Includes two individuals to determine if they are full, half, or have no sibling relationship, and a mother’s DNA is included at no additional cost. The cost also includes the DNA collection appointment, overnight shipping of the DNA samples to our lab, and legally admissible notarized results in two business days. Click here to learn more about a legally admissible sibling test.

You may order your test with a credit or debit card, PayPal, or with low monthly payments through our finance partner Affirm. Choose the option that is best for you when on our secure order form.

Sibling Testing Frequently Asked Questions

Here are the questions we are most often asked about siblingship testing. If you have questions that are not answered here, please reach out to us. We will always provide you direct and honest answers, and if we can’t help you, we may be be able to refer you to a company that can.

How Conclusive Are Your DNA Tests?

The results of a sibling test are shown as a probability percentage. This indicates whether the genetic profiles acquired can confirm the presence of a relationship. Results demonstrating a probability of 91% or higher are deemed as definitive proof that the relationship exists. Conversely, a probability of less than 9% establishes that the genetic evidence does not support the existence of the relationship. The statistics we show are guaranteed to be 100% accurate.

Can DNA Tell Which Brother Fathered A Child With A Sibling Test?

The answer is “Yes” in almost every situation. A sibling DNA test can determine which brother is the biological father of a child, if you include the DNA of the mother. Every child has genetic contributions (46 chromosomes) 23 chromosomes from the mother and 23 chromosomes from the father.

Can Your DNA Test Prove We Are Half Siblings?

Yes, our DNA test can prove you are half siblings. In fact, DNA testing is the most scientific and accurate way to prove that two or more individuals are biologically related. Half-siblings share only one biological parent, either the mother or father.

Can I Use The Results In Court?

We offer AABB accredited legal sibling testing which is valid in cases for child support, parenting time, birth certificate name changes, probate, and wills, as well as many other legal circumstances. A legally admissible DNA test requires some extra steps, however the final results will be the same.

Can You Tell If We Are Half-Siblings Or Cousins?

It depends. Since half siblings share 25% of the same DNA, and first cousins share 12.5%. Depending on if a mother’s DNA is available to test as well, there may be other testing options that would give stronger results. In these situations we encourage you to talk with one of our Genetic Consultants at 1-855-362-5224, or email us at info@dna-paternity-testing.com and we can offer advice on your unique situation.

Can I Test Something That Is Not A Mouth Swab?

Yes! Some commonly used items that are not a mouth swab include ear wax, hair, mucous on a tissue, finger or toe nail clippings, and toothbrushes. This may be a good option if the other person is not available for testing, or it is too difficult to approach them directly for a DNA sample. You can learn more about these “non-standard” DNA samples by clicking on Alternative DNA Samples, or call us a 1-855-362-5224.

How And When Will I Be Receiving My DNA Test Kit?

If you place your order before 2:00 PM PST, we will ship the same business day. We will send you a sterile DNA collection kit by Priority mail and email you a USPS tracking number. We ship Monday through Friday to physical addresses in the USA. Orders received after 2:00 PM PST ship the following business day. Depending on your location, USPS delivers Priority mail within 1-3 business days.

How Fast Can I Get My Results?

Once the lab has all of the samples available for sibling testing, we will have the results for you in 2 business days in almost every single case. We perform all DNA tests for siblings twice, to validate the findings. We do not charge any extra fees for this service.

Do I Need A Mother’s DNA For An Accurate Answer?

You can still do DNA testing without a mother’s DNA. We can still proceed, but we might need to examine more genetic markers. We begin with 24 markers, but sometimes we use up to 46 for stronger results. We’ll determine the need to add markers during testing. Additional markers might take an extra lab day, but no extra charge. These added markers aim for the best results. Your results will be 100% accurate with, or without, the mother’s DNA.

Can We Still Test If We Live In Different Cities?

Yes. When submitting your test order just indicate that you need more that the one DNA kit that is already included. If those being tested live close enough to get togther to collect their DNA samples, then only one kit is needed. If getting together isn’t possible, the we can send identical kit(s) to the other participant(s). Each kit will have identical case numbers, and the specimens are matched in lab by both the case number, as well as the names given on the order form. Each kit will also have a prepaid overnight label included (USA addresses) and we wil notify you once all samples have arrived and testing begins.