Special Services - DNA Twin Test


A question which is commonly encountered by families with twins is "are they identical or fraternal?" The twin zygosity test is used to conclusively determine whether twins are identical or fraternal.

Knowing whether twins are identical or fraternal is often difficult. Appearance alone often is not a reliable method in determining twin type because identical twins do not always look exactly the same, and fraternal twins can sometimes look very similar, leading to confusion about exactly what type of twins they are. Sometimes, twins grow up never knowing for sure whether they are identical twins or not.

At the time of birth, the physician will try to get an idea of whether twins are identical or fraternal by examining whether they share the same sac. Identical twins often form in a single sac, sharing a placenta and amniotic membranes. Fraternal twins often form in two separate sacs. However, up to 25% of the time, this method of determining twin type is not accurate and can be very misleading. In some cases, twins can have two sets of outer sacs (dichorionic) and still be identical twins. Also, the two placentas of fraternal twins can sometimes fuse together and appear to be one.

The only way to conclusively determine whether twins of the same sex are identical is through a simple DNA test. For this reason, many parents of twins will consider a private DNA test for twins to determine conclusively whether the twins are identical or fraternal. The DNA twin test is fast, simple and painless. A DNA sample is taken from each child by rubbing a painless swab gently inside the child's mouth for ten seconds. The samples are then submitted to the laboratory for testing and conclusive results are available within 5 days.

Legal or Private Testing?

In most cases, clients who choose to proceed with twin testing do not need to use the results in court and thus can proceed with a private sample collection procedure (home DNA collection kit). However, if you need to use the results of your twin test as supporting evidence in court, you will need to call our laboratory to schedule an appointment for chain-of-custody sample collection. During the appointment, we will verify the identity of everyone participating in the test and witness the collection procedure. This method of sample collection is only required if you are using the results in court. The steps outlined below are for private knowledge testing.

Quick Facts

Test Type DNA Twin Zygosity Test, DNA Twin Test
Individuals Involved Twins, Triplets
Description To determine the zygosity of twins, or determine whether twins are identical or fraternal.
Fee for Private Home Test [?] $180 US for testing twins
Fee for Court-Admissible Home Test [?] $255 US for testing twins
Fee for Legal Test [?] $355 US for testing twins, plus specimen collection fee
Specimen Buccal swab (blood is also acceptable but not recommended)
Turnaround Time Regular: 3 to 5 business days, Express: 2 - 3 business days
Method of Reporting Mail, Email, or Telephone
Ordering This test can be ordered by phone, fax, mail, or online:
  • By phone: 1-888-262-2263
  • By Fax or mail: download a printable Order Form
  • Order online: order online 24 hours a day


Step 1 - Order the test. Order laboratory testing by phone at 1-888-262-2263 or by mail, or order the private DNA collection kit online.

Step 2 - Collect and submit the samples to the laboratory. Kits are delivered to your door within 24 hours by courier or within 5 working days by mail. Each Maternity test kit comes complete with all of the collection materials and instructions for you to take the test in the privacy of your own home. All Maternity testing kits employ the buccal swab technique, allowing you to perform the collection within minutes with no fuss, no pain. Submit the DNA specimen directly to the laboratory after collection.

Step 3 - Wait for results. Twin test results are available within 3 to 5 working days (or as soon as 2 days for the express test) and can be obtained as soon as testing is completed using your secure order number and password online or by phone. Formal results documents are delivered to you by mail and / or E-mail. You may also call our laboratory to discuss your results over the telephone. To ensure the privacy and confidentiality of your case, we will confirm your password and file number before we discuss results over the telephone (the password and file numbers are provided to you when you order the test).

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