A sibling DNA test determines whether two people share one or both biological parents. It is the most common path forward when the alleged father can not be tested directly, whether he is unavailable, deceased, in another state or country, or chooses not to participate. We process every sample through an AABB-accredited lab, with an optional legal version for court use.
Sibling testing exists because life is complicated. The alleged father is not always available, willing, or even alive. When that is your situation, sibling testing offers a real path to a real answer.
He may be in another state or country, no longer in contact, or simply unreachable. A sibling test gets you an answer without him.
For inheritance, social security, or simply wanting answers after a loss, sibling testing lets you confirm a biological relationship without the father present.
Sometimes the father will not consent to testing. If you have access to one of his other children, a sibling test is the way forward.
Two people may know they are related but want to confirm whether they share both parents or only one. Sibling testing answers that exactly.
When an estate case requires proof of biological relationship and the father is unavailable, a legal sibling test is widely accepted.
For adults who suspect (or just learned) they may share a biological parent, sibling testing offers a discreet, private way to confirm.
Unlike a direct paternity test, sibling testing is probability-based. The lab compares DNA markers across both siblings and calculates how likely it is that they share one or both biological parents.
A simple cheek swab from each person. Painless, quick, and collected by an AABB Certified Technician at a location of your choosing.
If the known biological mother of either sibling is available, including her sample significantly strengthens the result. We recommend it whenever possible.
An AABB-accredited lab analyzes shared genetic markers between the participants using STR (Short Tandem Repeat) analysis, the same method used in paternity testing.
The result is reported as a probability. A high probability (typically 99% or above) supports a biological sibling relationship; a low probability indicates the participants are unrelated.
The test can also distinguish whether siblings share both parents (full siblings) or just one (half siblings), depending on which samples are included.
Delivered securely via email. Hardcopy mailed results available for $25. Legal results carry a notarized stamp for court use.
A direct paternity test compares a child to their alleged father, and the answer is essentially binary: 99.99% match or 0% match. Sibling testing is different because there is no single, direct genetic comparison to make.
Instead, the lab looks at how many DNA markers two siblings share and calculates the statistical likelihood of that pattern given a biological sibling relationship. Around 99.8% accuracy is achievable, and the result is stronger when:
If maximum certainty matters for your situation, ask us about including additional family members. We will recommend the strongest path for your specific case.
Mobile collection, certified specialists, AABB-accredited lab processing, and clear results.
Call or text us 7 days a week, 9 AM – 9 PM. A real person (not a robot) will walk through your specific situation and recommend the strongest test setup for your family.