Identical twins share almost all their genes, so any differences in their immune responses point directly to environmental factors.

The study will use the Snow Centre for Immune Health’s pioneering Cyton2 Cell Timer – a tool that tracks immune cell activity over time and turns a traditional static ‘snapshot’ into a video view. This dynamic perspective can reveal when immune cells activate, how long they persist, and why responses vary so widely between individuals.

By combining twin research with real-time immune tracking, the project aims to unlock practical advances in personalised medicine – from predicting who will respond best to a vaccine, to reducing treatment side-effects and guiding smarter prevention strategies.

Twin studies provide researchers with an exceptional scientific advantage not available in any other study design, offering a clear way to separate the effects of genetics from lifestyle and the environment.

Dr Lucas Calais-Ferreira, Director at TRA, said twins are special to research. “They help us to tease apart the effects of nature (genetics) and nurture (environment), and how they interact, in a way no other research design can.”

“By comparing identical and fraternal pairs, and by looking across ages and sexes, we can see what truly drives differences in immune responses.”

Based at the University of Melbourne, TRA is one of the world’s largest volunteer twin research registries. Its longstanding national registry is a major asset for the study, giving researchers access to a large, highly engaged pool of healthy volunteers.

“Many twins feel their role is special because joining with their sibling can answer questions only twins are uniquely positioned to answer,” Dr Calais-Ferreira said.

For decades, the question of what shapes our biology has been cast as a tug-of-war between genes and environment. More recent scientific advances indicate that nature and nurture effects also tend to build on each other through a person’s life. This study puts it to the test, offering new clarity for personalised medicine.

Because identical twins share nearly all their genetic code, any changes in their immune responses point squarely to environmental influences. While fraternal twins share about half their genes, like any other pair of siblings, they also share their early environment in a way that helps trace the importance of both genetics and the shared environment.

Comparing identical and fraternal twin pairs helps us quantify the relevant contributions of genes and environment. Once we know a person’s genetic background, we may be able to anticipate how their immune system might react and intervene before health problems develop.

Traditional tests give a single snapshot in time. The Cyton2 Cell Timer model reveals how and when immune cells act, and how long they stay active.

Professor Jason Tye-Din, Director of the Snow Centre said, “It is like switching from a photo to a video. You can see motion and timing that a still image cannot show.”

This dynamic view helps explain why some people respond well to a vaccine or treatment, and others do not. It can also show why some people have stronger side-effects.

• More targeted care: Doctors can match treatments to people more accurately.
• Fewer side-effects: Knowing genetic and environmental risks can guide safer choices.
• Smarter prevention: If a difference is environmental, we can change it.
• Better results at every age: Findings can guide age and sex‑specific care rather than taking a one‑size‑fits‑all approach.

“The Snow Centre brings cutting-edge immunology, and TRA brings decades of experience in twin research,” said Professor Tye-Din.

“Together, we can find answers neither could find alone and help many more people.”

Co-led by WEHI and the Royal Melbourne Hospital (RMH), in partnership with the Snow Medical Research Foundation, the Snow Centre brings together leading Australian and international researchers with a shared mission to transform how we research and treat the immune system. To find out more, visit snowimmunehealth.org.au

The study is seeking identical and non-identical twins aged 18-80. If interested, visit www.twins.org.au

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Header image: Professor Jason Tye-Din, Director, Snow Centre for Immune Health, Amanda and Nicole Campbell and Dr Lucas Calais-Ferreira, Director of Twins Research Australia.