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Twin Zygosity Test

Twin Zygosity Test

Twins (or their parents) curious whether they're identical or fraternal

Participants:
Two Twins
Lab processing:
2 business days after the lab receives your samples
$125.71

Quantity

1 pack·$125.71/test$125.71

Order with these add-ons (optional)

Overview

A zygosity test settles a common question: are the twins identical (from one egg) or fraternal (from two)? The lab compares the twins' DNA at many markers — identical twins match across all of them, while fraternal twins differ like any other siblings.

This is a private, peace-of-mind test. It is not chain-of-custody and not admissible in court.

What twin zygosity testing tells you

Identical (monozygotic) twins develop from a single fertilized egg that splits, so they share essentially the same DNA — close to 100% of their genetic markers match. Fraternal (dizygotic) twins develop from two separate eggs fertilized at the same time; genetically they are no more alike than any other siblings, sharing roughly 50% of their DNA.

The test compares the twins' DNA profiles across a large panel of markers. A match at every marker points to identical twins, while the ordinary differences you'd expect between siblings point to fraternal twins.

People choose zygosity testing for many reasons — plain curiosity, settling a lifelong family question, or practical relevance such as understanding shared genetics when thinking about health history. Whatever the reason, this is a private, peace-of-mind test for personal information only.

What you get

  • Cheek swabs for both twins
  • Step-by-step illustrated instructions
  • Pre-addressed return mailer or FedEx label
  • A private results report by email

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.

Turnaround timeline

  1. 1
    Kit ships — Within 1 business day of your order.
  2. 2
    In transit to you — A few days, depending on your location.
  3. 3
    You collect & mail back — At your own pace. The clock for lab processing has not started yet.
  4. 4
    Lab processing — 2 business days after the lab receives your samples.
  5. 5
    Results delivered — Sent to you privately by email.

Accuracy & methodology

Zygosity testing is highly conclusive: identical twins match at every marker tested, while fraternal twins show the expected sibling-level differences. Testing is performed by our accredited partner laboratory.

Testing is performed by our AABB-accredited partner laboratory.

Your privacy & trust

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.

Frequently asked questions

Weren't we told at birth whether they're identical?
Birth observations (such as one shared placenta) are often inconclusive. A DNA test is the reliable way to know for sure.
Is this admissible in court?
No. It is a peace-of-mind, informational test only.

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Need a legal DNA test?

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.