Twins Research Australia brings twins and researchers together for vital health research that benefits everyone.

Twins are special to research as they help us to tease apart the effects of nature (genetics) and nurture (environment) on our health. Our research impact has led to better diagnosis, treatment and prevention of a wide range of health conditions.

We also support twins and their families to live happy and healthy lives with comprehensive evidence-based educational resources.


We are Australia’s only national twin research centre of excellence and recognised as a world leader in this field. We bring twins and researchers together to undertake health research to benefit everyone.

We are based at the University of Melbourne, and undertake and support twin research in institutes and hospitals across Australia and globally.

Twins and their families make our research possible by volunteering to join in studies. Today, approximately 75,000 twins are TRA members or around 11 percent of Australia’s entire twin population. We are one of the largest volunteer twin research registers in the world.

The impact of our research is wide-ranging and widespread. We have contributed to new insights, prevention and treatment for some of the most challenging health problems of our times.

Find out more about our research and how twins make a difference.


Related links:

Twins Research Australia’s system of governance ensures accountability, fairness and transparency with all of its stakeholders.

TRA is managed by a Director and Deputy Director and administered by the University of Melbourne. 


We are very grateful to our Patron and Ambassadors for raising awareness and support for twin research and Twins Research Australia.


Please get in touch with us in any of the following ways:

 Mailing address


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


Google maps



General enquiries

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Phone: 1800 037 021 (freecall)

Fax: +61 3 9349 5815

Research enquiries 


Jessica Tyler
Research Coordinator and Liaison)

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Media contact


Lynette Walker
Marketing and Communications Coordinator)

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Phone: 0413 387 170



Twins and their families are at the heart of all that we do. We are dedicated to twin research and supporting twins to live happy and healthy lives - from newborns to twins of all ages, identical and non-identical. Please let us know how we can help you:


It doesn't matter how old you are, or if you are identical or non-identical, same-sex or opposite sex twins, well or ill - all are welcome to join us. Twins can be registered as soon as they are born (and up to the age of 18 - after which they can register themselves) by their parents.

Why are twins so important to research? By studying the differences and similarities between both identical and non-identical twins, researchers are able to to tease apart the effects of nature (genetics) and nurture (environment) on our health and wellbeing.

Our studies look at medical conditions that can affect anyone, such as cancer and diabetes, as well as issues of specific concern to multiple-birth families such as premature birth and twin social and educational development.

By joining us, you become part of something bigger - an amazing Australia-wide community of over 75,000 twins and their families joining forces to make a difference. Membership is free and designed to help twins to thrive, connect and belong.

As a member of Twins Research Australia, there are many ways for you to get involved: from joining a study, attending a forum or media event, to helping with fundraising. Even if you only have a few minutes to spare, you can make a valued contribution.


Are you a twin or triplet? A very precious gift that only you can give is the donation of your time to a twin study. By participating in twin studies, you'll be helping researchers to better understand what contributes to our health and happiness.

Below are our latest studies seeking twins and triplets. You'll find there are many ways to get involved - and often it is as simple as completing a questionnaire but this can be invaluable to research.

If you are interested in any, please click on the individual study link. We'll get back to you with further details. If you'd like to be alerted when a new study begins, please contact us. TRA and our researchers appreciate your time and interest.


Our researchers, with the help of twins, are working tirelessly to fast-track discoveries in medical fields with global impact such as obesity, diabetes, cancer, heart disease and mental health.

There are many ways to support the unique work of our researchers - whether you are an individual, twin, parent, community or work group, or business. By joining forces, we can make a world of difference.

Would you like to share a story about a unique aspect of your twin life? We’d love to hear stories of funny, fascinating or different experiences of being a twin.

These experiences might be personal, professional or linked to your involvement in a twin study. We are always looking for interesting stories to feature in our eNews or social media, or share with the media.

You never know where it might lead – it might make a difference to someone’s life, build awareness, support change, or simply entertain.

You can This email address is being protected from spambots. You need JavaScript enabled to view it.your story to us – 200-300 words would be ideal – and we’ll get back to you to confirm the details. We look forward to hearing from you.

We are pleased to answer your most frequently asked questions. If you have other questions not covered in our list please contact us and we'll be happy to assist. We also recommend following us on Facebook or Twitter and subscribing to our eNews as it is a great way to keep up to date with the latest in all twin related news.

Monozygotic (MZ) or identical twins

Identical twins occur when one fertilised embryo splits to form two individuals.

Identical twins are genetically the same; however, this does not mean that everything about them will be exactly the same. For example, while the fingerprints of identical twins are more alike than the prints of two completely unrelated people, they are not identical.

Identical twins are always the same sex; they usually are the same height, weight and have similar hair color. In relation to the genetic differences in MZ twins, different genes can be turned on or off which is why one identical twin may have a condition or disease that the other doesn’t. The differences are due to a number of natural chemical modifications that can influence changes to DNA – called epigenetics. Researchers have found that epigenetic changes in twins' genomes (their entire hereditary information) increase as the twins' age and become greater the longer they live apart. Common differences relate to features such as birthmarks, moles, hair patterns and teeth development. Aside from physical differences, there can be even greater differences in their personalities.  

Dizygotic (DZ) or non-identical twins

Non-identical twins occur when two separate eggs are released by the mother at the same time and are fertilised by two different sperm. These two fertilised eggs then implant independently in the uterus. DZ twins are genetically similar – just like normal brothers/sisters/siblings in that they share approximately 50% of their genetic material. DZ twins are still very special because they share the same womb and have very similar environments as they grow throughout life. 

Explore TRA's upcoming workshops, conferences and events here. 

Research news for multiple-birth families

An important part of our work is to translate findings from our research back to the multiple-birth community. With this in mind, we’ve prepared the following articles about issues of particular concern to multiple-birth families. You are welcome to re-publish and share the stories and photos throughout your community. There is a PDF of each article available to download, along with logos and other information you may find useful.

If you have other issues that you would like to see covered, please This email address is being protected from spambots. You need JavaScript enabled to view it.. You are also welcome to subscribe to our eNews (via the box on the right of each page) to access future stories.

About the event

Date and time: 7.30pm-9.00pm AEDT*, Thursday 18 November 2021

TwinsFest is the first-of-its-kind virtual twin event aiming to attract a national and global audience. It is hosted by not-for-profit Twins Research Australia, an eminent twin research institute based at the University of Melbourne. Established in 1981, TRA has undertaken over 250 studies involving thousands of volunteer twins and their families, and delivered breakthroughs to benefit the health of everyone.

TwinsFest is not only celebrating 40 years of twin research and the people who made it possible, but twin-ship itself and the unique experiences of twins and their families. The virtual event, aimed at adults, presents a festival atmosphere with entertainment, food and drinks, celebrity appearances, fun games (including a photo competition and trivia quiz) as well as great prizes to be won through a major raffle and silent auction. Best of all, it can be enjoyed by twins and parents – no matter where they live – from the comfort of their lounge rooms.

Most importantly, all proceeds from the night will go towards health research to benefit the wellbeing of twins and their families.

Please join us for this (virtual) festival like no other!

* Australian Eastern Daylight Time

Our latest news and events from Twins Research Australia

All the latest twins news from our researchers and around the world. 

Twins Research Australia regularly hosts conferences, training and events for the twin and researcher communities. If you would like to join our mailing list to be alerted about forthcoming conferences and events, please email This email address is being protected from spambots. You need JavaScript enabled to view it. or follow us on Facebook, Twitter or LinkedIn.

Explore TRA's past workshops, conferences and events here. 

Twins Research Australia’s blog for members and the broader twin community

Our videos and photo galleries showcase the unique lives of twins; why twins are so important to health research; and the many fascinating studies and findings of our researchers.

We share some of our videos and photo highlights below. See our full library at TRA’s YouTube channel.

The primary goal of Twins Research Australia is to facilitate, conduct and support research studies involving twins. These studies play an important and unique role in developing an understanding of good health, wellbeing and clinical problems from a genetic and environmental perspective.

Twin research utilises new technologies to establish the causes underlying the many health and medical issues that affect Australians and has the potential to fast track research. A twin study design is a valuable research tool for all medical and scientific researchers.

Twins Research Australia is a national twin research centre that maintains a registry of more than 35,000 twin pairs interested in participating in research and is involved in numerous research projects. Access to the resource is open to all researchers. 


For twins, zygosity refers to the degree of genetic similarity within each pair.

There are two different types of twins:

Dizygotic (DZ, fraternal) twins occur when two eggs are released at a single ovulation and are fertilised by two different sperm. These two fertilised eggs then implant independently in the uterus. DZ twins share around 50% of their genes which is the same type of genetic relationship as non-twin siblings, hence the term fraternal , and:

  • approximately half are the same-sex and half, different sex
  • each has its own placenta which is continuous with the chorion (outer membrane) with rare exceptions;
  • each is as genetically similar as any same-sex or different-sex siblings;

Monozygotic (MZ, identical) twins develop when one egg is fertilised by a single sperm and during the first two weeks after conception, the developing embryo splits into two. As a result, two, genetically identical babies develop.

  • approximately one third of MZ twins have separate placentas;
  • approximately two-thirds of MZ twins share a single placenta despite maintaining their own inner sac (amnion), umbilical cord and share of the placental mass;
  • all MZ twins are the same sex with rare exceptions;
  • are genetically identical, or almost 100% identical

A zygosity diagram can be downloaded here

A publication by the TRA team discussing why it zygosity determination is important for twins and science - and how the accuracy can be improved, can be downloaded here


Find out more:

(video credit: Open University©)

Research with twins has the potential to contribute transformative insights to our understanding of health and disease for us all. Specifically, twin research can play an important role in understanding the interplay between genes and environment. By studying the differences and similarities between and within twin pairs, crucial insights into complex diseases have been discovered. 

Research with twins can:

  • Estimate the impacts of genetic and environmental factors on why people differ in health and disease
  • Perfectly control for age and gender with a shared rearing environment.
  • Investigate discordance in disease or environment with a matching control; co-twin control study.
  • By naturally matching on variables such as age, gender and environment, twin studies can more readily identify the causes of diseases and health
  • Facilitate projects involving gender and disease with opposite sex pairs
  • Analyse issues relevant specifically to twins.
  • Provide a powerful model for epigenetic studies


 Website Buttons Researcher eNews 01



Twins Research Australia is a national twin research centre and comprises a rich resource of data, collaborative networks and twins available for research. We have over 35,000 pairs of twins available for research and health and lifestyle data for a sub-set of the registry.

Access to the twin registry is open to all researchers for research to benefit everyone.

Twins Research Australia’s collaborative networks extend to research groups nationally and internationally. In addition, more than 340 researchers have used the registry over the last 35 years which has enabled the twin design to be applied to a broad range of research areas including; musculoskeletal conditions, teeth, childhood pain disorders, epilepsy, educational outcomes, dementia, diabetes, cancer, cardiovascular disease and eating disorders.

Each quarter, Twins Research Australia produces a Researcher eNews bulletin showcasing interesting twin reseach being carried with twin data.  You can sign up to receive the eNews below.


 Website Buttons Researcher eNews 01


At Twins Research Australia, collaboration is central to all that we do. This ensures we contribute in the most effective way possible to generating new knowledge to medical research.

As Australia’s only Centre of Research Excellence in Twin Research (funded by the Federal Government’s National Health and Medical Research Council), we have a globally-renown team of experts that support our work. We also benefit from being a part of the broader education, research and teaching environment of the world-leading University of Melbourne.

Twins Research Australia comprises a leadership team of a Director, Two Deputy Directors, Chief Investigators and Associate Directors from institutes around Australia; supported by a management team. See our organisational structure.

Our passionate staff, leadership team, board members, and collaborators work in fields as diverse as research, public health, medicine, allied healthcare, law and ethics, population statistics, information technology, education, health promotion, administration, communications, marketing, finance, policy and advocacy.


Learn more about their individual skills and accomplishments:

Twins Research Australia is committed to developing long-term, mutually beneficial partnerships with research, community and corporate organisations that share our goals and values. Our partnerships reflect our local, state and national levels of operation. 

While TRA is based at the University of Melbourne, it collaborates with researchers in universities, institutes and hospitals throughout Australia. 

Partnership Logos

Twins Research Australia has a number of different tools and resources to assist researchers. Please click on the links below for more information:

This series of papers [ISSN: 2652-5518] aims to showcase the diverse application of the twin method to the research and health professionals' community, and to start a conversation regarding use of this approach in all areas of research, including education, early life origins of chronic disease, clinical trials and population health research. 

The appropriate study design and analytic method always depends on the specific research question and aim. The statistical model used depends on whether the outcome is continuous, binary or other (e.g.censored survival time, ordinal), and also (although to a lesser extent) on whether the exposure is continuous or binary. Although the exact study design and analytic approach may be unique to every study, here are some general classes of study designs involving twins and some statistical guidelines.

Things to keep in mind

  • More complex statistical methods are not always better (the simple paired t-test can be very useful in twin studies.)
  • General statistical principles still apply when analysing data from twins and families:
    • Explore your data thoroughly first
    • Be aware of model assumptions and test these whenever possible (e.g., normality, linearity and equal environments)
    • Provide estimates, 95% CIs and p-values
    • Start with simple analyses and models, and build on these
    • Adjust for measured variables before considering unmeasured effects
    • Analyses of continuous outcomes are usually more powerful than those of binary outcomes
  • Detailed advice should always be sought from a statistician if you are unsure.

Articles outlining the benefit of using twin designs can be downloaded below:


Broad classes of twin study designs & statistical packages:

Twins Research Australia

Address: 3/207 Bouverie St
Carlton, Vic 3010


ABN: 84 002 705 224

Twins Research Australia has received continuous funding from the National Health and Medical Research Council (NHMRC) since 1981, most recently through a Centre of Research Excellence Grant (2015-2022). TRA is administered by the University of Melbourne.

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