The question of whether our genes or our environment matter more for how long we live has lingered for decades. But a recent study published on April 21st, 2025 by Shenhar et al. may have finally tipped the scale. The authors reveal that genetics could account for twice as much of our lifespan as previously thought.

Environment plays a vital role throughout life, shaping early survival and long-term health. But its influence fades with age. Past a certain point, genetics becomes the dominant factor.

What is Heritability?

Heritability is the proportion of variation in a trait, like lifespan in this case, that can be explained by genetic differences between individuals. It’s not about how much your genes determine your life outcome, but how much they explain the variation across a population.

Researchers typically estimate heritability using:

• Twin studies: Comparing identical (monozygotic) and fraternal (dizygotic) twins.
• Pedigree studies: Tracking lifespans across extended families and generations.
• Genome-wide association studies (GWAS): Identifying specific genetic variants linked to longevity.

What the New Study Found: How Genetics Reclaimed the Spotlight

For decades, scientists estimated that only 7–25% of how long we live was inherited. But there was a major flaw in those numbers: they didn’t account for what kind of death occurred. Shenhar et al. made a critical distinction between two types of mortality:

• Intrinsic mortality – driven by biological aging and diseases like cancer or neurodegeneration.
• Extrinsic mortality – caused by accidents, infections, wars, or external hazards.

This matters because extrinsic deaths introduce random variation unrelated to aging. This random noise masks the true genetic signals, making heritability look lower than it really is. Using mathematical modeling and data from twin studies, the researchers showed that:

• Early deaths from extrinsic causes weaken the observed genetic link between twins.
• When these deaths are excluded, the genetic contribution becomes much clearer.

In more developed societies with lower extrinsic mortality, heritability estimates for lifespan increased dramatically, rising to over 50%.

Environment vs Genetics

Both environment and genetics matter but not equally and at a different time.

In early life, environment plays the dominant role: clean water, nutrition, healthcare, exposure to disease. These factors determine who makes it through infancy, childhood, and young adulthood. This accounts for public health and lifestyle.

But once you've reached midlife and old age, genetics takes over. The Shenhar study confirms what longevity researchers have long suspected: the longer you live, the more your lifespan is shaped by your DNA.

That’s why centenarians (people who live past 100) and supercentenarians (those who reach 110+) are often described as genetic outliers. Despite varied diets or lifestyles, they tend to carry rare variants in genes linked to DNA repair, inflammation control, or stress resilience.

Natalie Coles, a longevity researcher who studies supercentenarians, confirms it’s not their lifestyle but their genes that set them apart.As Shenhar et al. show that the genetic contribution to lifespan become unmistakably dominant especially past age 60, after removing early, random deaths from the equation.

What This Means for the Individual

That doesn’t mean lifestyle doesn't matter. It just means that some people may be genetically better equipped to resist age-related diseases, repair cellular damage, or maintain vital functions longer.

In the near future, your genes might shape your health plan. Advances in aging research are enabling for:

• Early warnings: Genetic risk scores could flag individuals more prone to faster aging or age-related disease, enabling medical interventions
• Tailored therapies: Drugs like rapamycin may work better in people with specific genetic signatures.
• Real-time tracking: Tools like epigenetic clocks may one day monitor how well your anti-aging strategy is working.

Aging is shaped by genetics, environment, and lifestyle, so genetic risk scores may have limited predictive power on their own. But the trend is clear:

The future of longevity might still be precision-guided.

What This Means for Biotech

If genetics drives more than half of how long we live, genetic solutions will be essential.

For biotech, this shifts the focus from treating age-related diseases after they appear to identifying and targeting the underlying risk factors encoded in our DNA.

That could mean:

• Developing therapies tailored to individual genetic profiles
• Creating drugs that activate or repair key longevity pathways, like DNA repair, inflammation control, or cellular cleanup
• Using biomarkers like epigenetic clocks to measure whether treatments are actually slowing biological aging

As this field evolves, we may move from broad “anti-aging” approaches to precision longevity medicine, where interventions are based on your DNA.

We’re Excited about MatterBio

One company already pushing the frontier is MatterBio, a standout in the LongBio space. Backed by George Church, the legendary Harvard geneticist behind the foundational technologies of gene editing and synthetic biology, MatterBio is advancing a bold idea: democratize longevity genes.

Their mission? To take the rare genetic variants found in centenarians and supercentenarians, and make them accessible to everyone. But they’re not stopping with human DNA. MatterBio is also exploring the genomes of the longest-living species on Earth, like the Greenland shark, which can live over 450 years, and translating their cellular resilience into gene therapies for humans.

This is the kind of visionary science that could redefine what’s possible for human lifespan and make longevity a programmable feature of the future.