Contact us

Thank you for your query.

You may be able to find the answer quickly to your question at our FAQs below. We’ve grouped our most popular questions under main headings. Click on any of the questions for further information.

How to become a TRA member?

I’d like to become a TRA member. How do I join?

Thank you for your interest in joining our wonderful volunteer community! 
If you’re aged 18 years and above, register using the adult twin registration form.
Twins under 18 years of age can be registered by a parent or guardian using the junior registration form. Membership is free!

Can non-identical and opposite sex twins join? What age? What about if I have a pre-existing medical condition?

Twins of any age can join us – from 0-100+ years old! They can be registered as soon as they are born (and up to 18 years old) by their parents. Adult twins (18+ year old) register themselves. It doesn’t matter if you are identical or non-identical, same-sex or opposite sex twins, well or have health conditions – all are welcome to join us. 

I’m not sure about becoming a member. What is involved?

Find out more about becoming a TRA member here

Existing members

My email address, name, phone number (or other details) have changed. How do I update my member details?

You can easily update your contact details here 

Research studies 

When will I be invited to join a study?

When a new study begins, TRA emails invitations to members who might be eligible to participate so they can decide if they would like to be involved. You might get a study invitation within a few months however sometimes it can take a few years. You can check out your eligibility for our current studies

Are the details of my membership and study participation kept private?

Information concerning TRA members is kept strictly confidential; personal details are NEVER given to researchers or any other party without the express permission and consent of the individual member. Learn more here

I’m part of a study and have some questions about it. Who do I contact?

Please first check the information on this page where our currently recruiting studies are listed. If you still have a question, please email us

DNA/zygosity testing

I’m not sure if my twins are identical or fraternal. How can I find out for sure?

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 share 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 identical (monozygotic) or fraternal (dizygotic). The best way to be certain is to do a simple pain-free zygosity test, using samples of DNA from the babies (such as swabs taken from the inside of their cheeks). 

Where to access zygosity testing?

An Australian organisation, EasyDNA, currently provides the most competitive discounted zygosity testing rate available, which is exclusive to members of Twins Research Australia. If you would like to access this after your babies are born and you have registered to become a TRA member, you can visit the TRA website page here to request your discount code before arranging the test through EasyDNA

About twins

My twin and I are identical, but we look different and have different health issues. How can twins who share the same genes be so different?

Article being updated. Please return to the page soon.

Twin pregnancy and parenting 

I’m expecting twins. Do you have any resources about twin pregnancy?

Firstly, congratulations on this exciting news! We have a free microsite containing comprehensive information about twin pregnancy and birth, and what to expect when your babies go home. You can request free access to the website via this link

My twins each had their own placenta. Does this mean they are fraternal twins (dizygotic)?

Not necessarily as approximately a third of monozygotic (identical) twins each have their own placenta. Learn more here

Are twins hereditary?

While there has not been any research to show that identical twinning can be inherited; non-identical twinning can be. Article being updated. Please return to the page soon.

How many twins are there in Australia?

The population of Australia is around 25.4 million, so there are approximately 750,000 multiples (based on an estimate of 3% of the population is a multiple). More stats here

Are there more fraternal twins than identical twins?

Generally, about 1 in 80 births in Australia is a twin and, of these, about 30% are MZ and 70% fraternal.

What is Twin to Twin Transfusion Syndrome (TTTS)?

This is a condition affecting identical twins when the babies share a common placenta while in the womb. This can lead to problems in both twins as one twin can receive too much blood (the ‘recipient’ twin), and the other too little (the ‘donor’).

The ‘donor’ twin is usually much smaller than the ‘recipient’ twin and can have complications such as anaemia, slower growth and dehydration. The extra blood received by the ‘recipient’ twin can place strain on their heart. They also have excessive urinary output resulting in increased amniotic fluid, while their co-twin suffers the opposite fate. Early detection is key to ensuring best outcomes for both babies – discuss with your health carer if any concerns.

My twins shared a placenta. Does this mean they are identical?

Almost always, bearing in mind (1) sometimes fused placentas get mistaken for a single placenta and (2) an extremely small proportion of one-placenta twins are chimeric fraternal twins whose placentas must have fused early in development. If you are at all in doubt, a simple pain-free zygosity test will resolve the issue.

Support services 

Looking for practical support and services, twin specific psychologists and mental health advice, 24-hour phone services, online community groups and much more?

For practical support and services, and contact numbers, visit here  

Still have a question? Please email us at


Twins Research Australia
Centre for Epidemiology & Biostatistics 
Melbourne School of Population & Global Health
The University of Melbourne
Level 3, 207 Bouverie Street
Victoria, Australia 3010

Research enquiries

Jessica Tyler
Research Coordinator and Liaison

Media contact

Lynette Walker
Marketing Communications Coordinator

Member support


We are a small team with our focus on conducting as many research studies as possible to find cures faster. The nature of our work means emailing is the best way to contact us. We do provide a freecall number 1800 037 021 but we monitor this irregularly.  We ask our supporters to only use this after (1) checking FAQs above and (2) emailing us with your query. Thank you for your understanding and patience.