Why do some people live well into their 90s or beyond while others develop age-related diseases much earlier?
Scientists have long investigated whether part of the answer might be hidden in our genes.
But decades of research have revealed something important: there is no single gene for longevity.
Many genetic variants have been associated with living longer, but only a small number have been repeatedly identified across different populations.
One of the strongest examples is APOE. Different variants of this gene are associated with different risks of cardiovascular disease, Alzheimer’s disease and survival into advanced age. Another important gene is FOXO3, which has been linked to longevity in several populations and is involved in processes such as metabolism, cellular stress responses and maintenance.
But neither APOE nor FOXO3 determines how long someone will live.
Instead, human longevity appears to be a complex genetic trait. Many genetic variants may each contribute a small effect, working together through biological systems involved in maintaining health and protecting against disease.
This has changed the way scientists study the genetics of longevity.
Rather than searching only for individual “longevity genes,” researchers increasingly investigate networks of genes and the biological pathways they influence. These include pathways involved in metabolism, DNA repair, immune function, cholesterol regulation and telomere maintenance.
Genes are also only part of the equation.
The genetic characteristics we inherit interact throughout life with our environment, lifestyle, health conditions and many other biological influences. Even people with similar genetic backgrounds can therefore experience very different patterns of aging.
Our genes may influence our chances of living a long and healthy life-but they do not write the entire outcome in advance.
