Healthy ageing shaped by more varied biology than previously thought

3rd September 2026 – by Kings College London

People of the same age can experience very different biological changes as they grow older, according to new research led by King’s College London using data from TwinsUK.

Published in Science, the study is one of the most detailed long-term investigations of molecular ageing to date. It shows how genetic factors and environmental influences interact over time, shaping individual ageing journeys.

Researchers repeatedly measured molecular changes in 335 TwinsUK participants over eight years, examining blood RNA levels, the activity of around 16,000 genes and hundreds of metabolites. They found that some participants experienced markedly different, and sometimes opposite, changes despite being the same age and considered healthy.

The team identified differences in the way people’s molecular profiles changed over time, including changes involving CXCL9, a gene linked to cardiac ageing. They also found that levels of TP53, a tumour suppressor gene, declined with age in some participants, potentially affecting their cancer risk.

The findings suggest that molecular changes associated with ageing are not the same for everyone. Differences may reflect genetic predispositions or environmental exposures, offering clues to why some people are more susceptible to certain age-related conditions than others.

The researchers also identified associations between environmental exposures and changing molecular profiles, including shifts in blood levels of PFAS, often known as “forever chemicals”. This highlights how environmental factors may be reflected in the body’s biology over time.

Dr Julia El-Sayed Moustafa, Research Fellow at King’s College London and first author of the study, said:

“Rather than there being a single molecular roadmap of ageing, our study shows that people follow distinct biological journeys. Two healthy people of the same age can be ageing in surprisingly different ways at the molecular level. That raises the possibility of much more personalised approaches to predicting disease risk and maintaining health as we grow older.”

Professor Kerrin Small, Professor of Genomics at King’s College London, said:

“Our findings suggest that human ageing at the molecular level is not a uniform process, but one that is dynamic and environment dependent. Understanding individual molecular ageing trajectories may eventually help distinguish healthy ageing from the earliest stages of disease and identify opportunities for earlier, more personalised interventions. Our study could help provide a roadmap for precision medicine.”

Ageing involves gradual changes to cells and key molecules, including DNA, proteins and lipids. Over time, these changes can affect tissue function and contribute to a higher risk of conditions such as cancer, cardiovascular and metabolic diseases, and neurodegenerative disorders.

By showing how these changes vary between individuals, the study provides a more detailed picture of healthy ageing and could help researchers develop more personalised approaches to understanding disease risk and supporting health as people grow older.