Zygosity testing

How can twins be sure of their zygosity i.e. whether they are identical or fraternal twins?

Research has shown that up to one-third of twins may be misinformed or unsure about their zygosity. Learn about why this occurs and why it is important to know your zygosity here

  • If you have a boy and a girl it’s easy, they will be non-identical or dizygotic (with very rare exceptions)
  • If they are of the same sex and definitely shared one placenta it’s also easy, they are almost always identical or monozygotic
  • If they are of the same sex and each had a placenta, or if there is doubt about the type of placenta, then they could be either identical (monozygotic) or fraternal (dizygotic)

The best way to be certain is to do a zygosity test.

Discounted zygosity testing for TRA members

An Australian organisation, EasyDNA, provides a special discounted zygosity testing rate exclusive to members of Twins Research Australia.

The test is via a cheek swab with results within just seven working days. Your test kit is posted to you.
Please read EasyDNA’s Terms and Conditions prior to placing your order with them.

Their special discount of $29 off their usual rate of $199 (+ postage) is available to TRA members only. If you’re not already a member, learn how to join us. Membership is free.

To request a zygosity test and obtain the special $170 rate (per twin pair), you simply need to:

  1. If you are a TRA member, contact us on info@twins.org.au to obtain the unique discount code
  2. Enter the EasyDNA site*: https://easydna.com.au/dna-tests/twin-dna-test/
  3. Click the ‘Order Now‘ link on the product page
  4. Select the test order options as desired and click ‘Next‘ to order (we recommend stating that you are a TRA member in ‘Comments‘ on this page)
  5. Complete all personal and order details. You will need to put the code provided to you by TRA in ‘Discount Voucher Code‘. Please note that only valid ID’s will receive the discount and will be verified by TRA
  6. Click ‘Proceed to Payment‘ to then enter payment details and to complete your order. (Note: if an invalid code was entered, you will be alerted and taken back to the ‘Personal Details’ page)

    * If ordering a kit by phone (1300 482 165) please inform the customer care agent that you are a TRA member and provide your TRA ID. Your discount will be applied once your ID has been verified by us