Become a member

It doesn’t matter how old you are, or if you are identical or fraternal, same-sex or opposite sex twins (or a Higher Order Multiple), well or with an existing medical condition – all are welcome to join us.

Twins and HOMs can be registered as soon as they are born. Those under 18 years of age can be registered by a parent or guardian using the junior registration form.

If you are over 18 years of age, you can register as an adult using the adult twin registration form
Please note that both twins will need to join Twins Research Australia, therefore please include your co-twin’s email address on the registration form where requested and they will then receive a link to register themselves.

We will send out a welcome email to all newly registered pairs. If you do not receive one, please contact us.

Please note: If you or your twin (or your parents) are already receiving communications (e.g. study invitations, eNews) directly from TRA, you are already a member. Please do not re-register. Instead, update your contact details.

Find out more:

Why join?

When you join Twins Research Australia, you are part of something bigger. TRA represents an amazing Australia-wide community of over 75,000 twins (and their families) who share insights from their special twin relationships for better health for all.

Our hope is that you are able to thrive, connect and belong as a member of our community.  


  • Receive invites to join relevant studies and findings of any study in which you participate
  • Keep informed about the latest twin health studies and their findings through our regular eNews and website resources
  • Access to discounted genetic (zygosity) testing – find out why this testing is important here and register for testing
  • Access to practical and evidence-based free resources such as the Twin Pregnancy and Parenting website  
  • Some studies offer different health tests, for example, for eyes, teeth, bone density, and heart


  • Connect with other twins and their families through our social media channels: Facebook and Instagram
  • Receive invites to special twin events like festivals and forums


  • Benefit from the ‘happiness effect’ – many studies show volunteering and helping others can help reduce stress, combat depression, keep mentally stimulated, and provide a sense of purpose
What is special about twin research?

You may be wondering why twins are special to research.

All twins share a lot in common, starting from conception. By comparing the similarities and differences between identical and fraternal twins, researchers are able to better understand how genes (nature) and environment (nurture) influence our health.

By looking into environmental and genetic influences on medical conditions – such as cancer, diabetes, obesity, mental health, brain ageing and heart disease – we can improve prevention, diagnosis and treatment for them.

Our research also looks at issues of specific concern to multiple-birth families such as premature birth, and twin social and educational development.

When you join our research, you are supporting not only families like yours but our whole community.

What is involved?

Twins who register with Twins Research Australia are placed on our database and are contacted when there is an appropriate study.

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, and you can withdraw from a study at any time.

Time taken to support a study can be as little as a few minutes filling out an online questionnaire. Some studies include clinic visits that offer different health tests e.g. for eyes, teeth, bone density, and heart.

All research conducted or facilitated by TRA meets stringent ethical guidelines, particularly regarding the involvement of babies and children. The comfort, safety and wellbeing of all research participants are of paramount importance. We will always be very clear about what is involved in any study so you can make an informed decision if it is right for you and your family.

Please note: information concerning individuals of TRA is strictly confidential; personal details will not be given out without your consent.

Join a study

Once you become a TRA member you can join any of our current studies that you are eligible for.

Browse our studies here.