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Siblingship DNA Tests

Find out whether two people are full siblings, half siblings, or unrelated — privately, for your own peace of mind.

A siblingship test estimates whether two people share one biological parent (half siblings), both parents (full siblings), or none. It's a common question when an alleged parent isn't available to test, or when adult siblings want private clarity about their family.

Sibling relationships are more nuanced than paternity. Full siblings share about half of their DNA on average, half siblings about a quarter — but the exact amount varies from person to person. That's why results are reported as a likelihood rather than a simple yes/no, and why including a known parent makes the answer much clearer. As with all of our tests, siblingship testing here is for personal peace of mind, not legal use.

Siblings tests

Full Siblingship Test (With Common Parent)

Full Siblingship Test (With Common Parent)

Two people checking whether they share both parents, with a known parent available

Participants:
Two Siblings, One Common Parent
Lab time:
5 business days
$179.99View test →
Full Siblingship Test (Without Common Parent)

Full Siblingship Test (Without Common Parent)

Two people checking whether they share both parents, no parent available

Participants:
Two Siblings
Lab time:
5 business days
$179.99View test →
Half Siblingship Test

Half Siblingship Test

Two people checking whether they share one biological parent

Participants:
Two Siblings (common parent optional)
Lab time:
5 business days
$179.99View test →

How it works

  1. 1

    Order your kit

    Choose your test and check out online. No appointment or doctor's order needed.

  2. 2

    We ship within 1 business day

    Your collection kit ships free with cheek swabs, step-by-step instructions, and a return mailer.

  3. 3

    Collect samples at home

    Each participant gently swabs the inside of their cheek. Painless and takes about a minute per person.

  4. 4

    Mail samples to the lab

    Drop your samples in the mail using the supplied envelope. Prepaid Return Mailer or FedEx Overnight Label Provided. Lab processing time starts when the lab receives your samples.

  5. 5

    Receive results securely

    The lab sends your report to us and we forward it to you privately by email.

Who uses this test

People turn to siblingship testing in situations like these:

  • An alleged parent can't be tested, but two possible siblings can.
  • Adult siblings want to privately confirm whether they share one or both parents.
  • Reconnected family members — for example, after an adoption or a discovery through an ancestry service — want to understand their relationship.

A siblingship test can give you a well-founded likelihood for your own information, and that likelihood gets stronger when a known parent participates. It cannot provide legal proof of a relationship — for inheritance, immigration, or any court matter you'll need a court-approved, chain-of-custody test.

What you’ll need

  • The cheek swabs included in your kit — no needles, no blood
  • Both people whose relationship you want to compare
  • A known common parent if available — it strengthens the result considerably
  • Consent from every adult participant

Accuracy & methodology

Siblingship analysis compares how much DNA two people share and calculates how likely that pattern is for the relationship in question versus unrelated people.

  • Results are reported as a combined sibling index and probability.
  • Full vs. half: the lab can usually distinguish full siblings from half siblings, because they share different average amounts of DNA.
  • Including a parent lets the lab account for one side of each person's DNA, sharpening the result and helping resolve borderline cases.
  • Some relationships are inherently harder to call from DNA alone; the lab will recommend adding a parent where it helps.

Testing is performed by our accredited partner laboratory.

Testing is performed by our AABB-accredited partner laboratory.

Frequently asked questions

Why is a sibling result a probability instead of yes/no?
Siblings share only part of their DNA, and the exact amount varies. The lab calculates how likely the observed sharing is for the relationship being tested versus unrelated people, and reports that as a probability.
Can the lab tell full siblings from half siblings?
In most cases, yes. Full and half siblings share different average amounts of DNA. Including a known parent improves the lab's ability to distinguish borderline cases.
Do I need a parent to test?
No, but it helps a lot. We offer tests with and without a common parent; including one produces a considerably more conclusive result.
Is this admissible in court?
No. Siblingship testing here is for personal peace of mind only. Legal matters such as inheritance or immigration require a court-approved, chain-of-custody test.
How long does it take?
Lab processing is typically about 5 business days from receipt of samples. Counting kit shipping and your collection and return time, plan for roughly 3–6 weeks end to end.
What if we don't share the parent we expected?
The test reports the most likely relationship the DNA supports. If the result is unexpected or borderline, the lab may suggest including a parent to clarify.

Related tests & legal note

If you're really trying to establish a relationship to a specific parent, a direct paternity test (or, when a parent is unavailable, a grandparentage or avuncular test) may suit you better. For shared deep ancestry rather than close relationships, see our Y-chromosome and mtDNA lineage tests.

Need a legal result? Siblingship testing here cannot be used in court, for inheritance, or for immigration. Those require a court-approved, chain-of-custody DNA test through an accredited laboratory.

Need results for a custody case, child support, immigration, or any other legal matter? An at-home test cannot be used for those purposes. You'll need a court-approved, chain-of-custody DNA test performed through an accredited laboratory, where a neutral third party verifies every participant's identity and handles the samples.

Privacy & data handling

Your privacy matters to us, and DNA information is among the most sensitive personal data there is.

  • Samples are used only to perform the test you ordered and are destroyed after testing is complete. <!-- TODO: confirm exact sample-retention window with fulfillment lab before publishing -->
  • Results are delivered privately by email and are never sold, rented, or shared with third parties for marketing.
  • Your DNA data is treated as sensitive personal information. While at-home, informational tests are generally not covered by HIPAA, we handle your results with comparable care.
  • You can request deletion of your records at any time by contacting us.