At Twins Research Australia, we are frequently contacted by parents and twins who are unsure whether they are identical or not. Often this is out of pure curiosity more than anything else.

However, we believe that knowledge of zygosity is not only critical for twin research, but also for the twins themselves and their families. Knowing zygosity has implications for health and medical treatment (e.g. transplant compatibility), education and social development and the probability of having more twins (there is a genetic component to having non-identical twins).

We now offer discounted zygosity testing for TRA members!

TRA has negotiated a special discounted rate with easyDNA – exclusive to TRA members. Head to this link to learn more.

What is TRA?

Twins Research Australia was established in 1981 to serve as a link between researchers, twins and higher-number multiples who are interested in getting involved in research projects. With over 75,000 members, TRA has become the largest volunteer registry of multiples in the world. Nevertheless, this still only represents about 10% – 15% of twins in Australia and we need more recruits!

It doesn’t matter how old you are - if you are identical or fraternal, well or ill, boy, girl or opposite sex pair – all are welcome to join.

Why are twins so important?

By comparing the similarities and differences between identical and non-identical twins, researchers can get a better understanding of how our genes and environment determine who we are, what we do and our future health and happiness. In addition, by studying boy/girl twin pairs, researchers can discover important information about gender differences in certain diseases and conditions.

What does being a member involve?

We always have new studies coming up – you may be interested in some and not others and that’s fine – you always have a choice whether to participate or not.

Parents can register their multiples as newborn babies. Children of all ages can join but must be registered by their parents if they are under 18 years of age.

Multiples who register with TRA are placed on our database and are contacted when there is an appropriate study – which is often only once a year. In fact, it may even be a few years before you are sent your first invitation! Your involvement is always voluntary and you can withdraw from a study or TRA at any stage. Common activities include filling in questionnaires and health and lifestyle checks.

How can I find out more information?

  • Freecall 1800 037 021
  • Visit our website
  • Register online here
  • Request a free booklet for women pregnant with multiples or for families with newborn multiples
  • Find our most frequently asked questions relating to multiples here

You can also connect with us on Facebook, Instagram and Twitter.

(You are welcome to download a PDF of this story here and re-publish in your club eNews)

Twins Research Australia

Address: 3/207 Bouverie St
Carlton, Vic 3010

Freecall: 1800 037 021


ABN: 84 002 705 224

Twins Research Australia is a national resource supported by a Centre of Research Excellence Grant from the National Health and Medical Research Council and housed within the University of Melbourne.

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