A Parent Is Unavailable
When the alleged father is deceased, absent, or unwilling to test, comparing siblings is an effective indirect way to establish whether they share that parent.
99.99%+ Accurate · Confidential · Results in 3-5 Days
Sibling DNA Test
“Will I get a clear, reliable answer?” “How soon will I know?” “Can I talk to someone who will not judge me?”
A sibling DNA test determines whether two people share one or both biological parents. TestMark DNA makes it simple: order an at-home kit online, or test at one of 2,297+ certified locations. Painless cheek swab, confidential results in 3 to 5 business days.
Same-day testing available at most locations
Talk to a real DNA specialist, never a phone menu. Free consultation, no obligation, at (866) 702-7644.
AABB-Accredited Labs
99.99%+ Accuracy
Confidential Results
Results in 3-5 Days
Discreet
Certified Network
Results in 3-5 Days
Confidential
2,297+
Certified Collection Sites
50
States Covered
99.99%
Accurate Results
We know this is about more than a test.
Whether this is for you or someone you love, this can be a stressful and deeply personal moment. We have helped thousands of families get clear answers with care, respect, and zero judgment. From your first call to your final report, you will not navigate it alone. And if you are still gathering information, that is okay too. Call with your questions before you are ready to decide. There is no pressure, and a real specialist is glad to help.
When Is Sibling Testing Needed?
A sibling test is the answer when you need to confirm a biological relationship but a parent cannot be tested directly. These are the most common reasons people order one.
Inheritance & Estate Claims
Confirm shared parentage to support a claim to an estate or to document a biological sibling relationship for probate and inheritance matters.
Social Security & Immigration
Prove a sibling relationship for Social Security survivor benefits or for an immigration petition that asks you to document shared biological parentage.
Family Lineage & Peace of Mind
Reconnecting after adoption, or matched through an ancestry database? A sibling test confirms whether you are full siblings, half siblings, or unrelated.
Find out if you share a parent
Order an at-home kit, or call and we will set up each participant at a location near them.
Call for a Free Consultation - (866) 702-7644Prefer to order online?
Order Your Sibling Test OnlineHow it works
Call for a free consultation
Our team walks you through the right test, answers your questions, and confirms your nearest location.
(866) 702-7644Visit your local collection site
Collect samples at home with the painless cheek swab in your kit, or visit one of 2,297+ certified collection sites. Each sibling can test at a different location, and the lab begins once all samples arrive.
Get results in 3 to 5 business days
Receive your confidential results delivered securely. Over 99.99% accurate, private, and legally defensible.
Call for a free consultation
Our team walks you through the right test, answers your questions, and confirms your nearest location.
(866) 702-7644Visit your local collection site
Collect samples at home with the painless cheek swab in your kit, or visit one of 2,297+ certified collection sites. Each sibling can test at a different location, and the lab begins once all samples arrive.
Get results in 3 to 5 business days
Receive your confidential results delivered securely. Over 99.99% accurate, private, and legally defensible.
Legal vs Personal DNA Testing
LEGAL
Legal DNA Test
- Court-admissible results
- Chain-of-custody documentation
- Government ID required at collection
- Results accepted in legal proceedings
- Collected at certified site only
PERSONAL
Personal DNA Test
- For personal knowledge only
- No chain of custody required
- No ID required
- Results not for legal use
- Can collect samples at home
Both options available - call to confirm which is right for your situation.
Not sure which test you need? Call for a Free Consultation - (866) 702-7644Simple Pricing, No Surprises
$199
A complete sibling DNA test. Order online or by phone.
Sibling testing is priced by test type and number of participants. Adding a known parent strengthens the result and may change the price. Legal tests cost more than personal tests because they include chain-of-custody documentation. There are no hidden fees, and we confirm your exact price before you book, at no cost.
No Hidden Fees
We quote your full price up front during the free consultation. No surprises.
Free, No-Obligation Call
There is no charge to call, ask questions, or get pricing. You only pay if you decide to test.
Order Online in Minutes
Prefer not to call? Order and pay securely online whenever you are ready.
Frequently Asked Questions
What does a sibling DNA test tell me?
It tells you whether two people are full siblings (sharing the same mother and father), half siblings (sharing only one parent), or unrelated. The laboratory compares each person’s genetic markers and calculates a siblingship index, the statistical likelihood that they share parentage.
How accurate is sibling DNA testing?
Sibling testing is highly accurate, but unlike a paternity test the result is reported as a probability rather than a simple yes or no. Because siblings inherit a random mix of DNA from two parents, accuracy improves substantially when a known parent also tests. The lab analyzes a minimum of 20 STR markers for reliability.
Should the mother or another parent be included?
Yes, whenever possible. Including a sample from a known parent significantly improves the statistical strength of the result, because the lab can subtract that parent’s contribution and focus on the markers in question. It is not strictly required, but it leads to more conclusive results.
Can a sibling test be used instead of a paternity test?
Yes, as an indirect method when the alleged father cannot be tested, for example if he is deceased, absent, or unwilling. Direct paternity testing is more conclusive when it is an option, but sibling testing provides recognized scientific evidence when it is not.
Can sibling results be used in court or for benefits?
Only if you order a legal sibling test, which is collected at a certified site with photo ID verification and a documented chain of custody. A personal or at-home test is for private knowledge only and is not admissible for court, Social Security, or immigration.
How are samples collected and how long do results take?
A painless buccal (cheek) swab is gently rubbed inside each participant’s cheek for a few seconds, and participants can test at different locations. Samples go to an AABB-accredited laboratory and results are typically ready within 3 to 5 business days after the last sample arrives. Call (866) 702-7644 for a free consultation and exact pricing.
Get your sibling test started today
Accurate, confidential, results in 3 to 5 business days.
Call for a Free Consultation - (866) 702-7644Prefer to order online?
Order Your Sibling Test Online