Lifespan is 55% Genetic: What does that mean for your Longevity goals?
In the game of life, good genes could give you an outsize edge. But you still need to bank on lifestyle to hit the jackpot.
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Creative by Anjul D.| Genes determine if you celebrate your 100th birthday. Lifestyle gets you there.
Genes control 55% of your Lifespan.
Lifestyle accounts for the remaining 45%.
A new research paper studied twins’ lifespans across Scandinavia and the US. Its key finding: our genes have a larger impact on lifespan.
Yes. The ‘heritability’ of our longevity could be as much as 55%, per this study from the Weizmann Institute.
Put simply, this means we are born with almost half of our lifespan already coded into the DNA we get from our parents. The remaining 45% is shaped by our lifestyle.
Interestingly, the results align with the ‘heritability’ observed for most genetically-determined human physiological traits (like the colour of your eyes or hair). It is also similar to the heritability of lifespan observed in other species.
Another important detail – the study also looked at the ‘heritability’ of diseases. Turns out, if parents in a family have cardiovascular disease or Dementia, there is a high chance the children will also develop it.
However, heritability is much less in case of Cancer. This suggests there is a higher chance Cancers develop because of external triggers or random cellular mutations in the body, not because someone in the family had it.
How did researchers conclude Genetics has the upper hand?
They did that by filtering out the ‘noise’ in the data.
Now, earlier studies on lifespan had used data from people born before the 19th century – well before vaccinations, sanitation, antibiotics and hygiene and safety regulations existed. Most of these people typically died of infectious diseases.
For this new study, researchers pulled out twin studies from Denmark and Sweden dating back to the 1800s. They also added recent data on American siblings – specifically children of long-lived people. Then they used a mathematical model to filter out all deaths linked to ‘extrinsic’ factors like infectious diseases, accidents, disasters etc. And crunched the numbers.
The logic – Identical twins share 100% of their DNA, fraternal twins share about 50%. Comparing lifespans of the twins within and between these groups would help estimate the contribution that genes make to lifespan (any variance would be lifestyle-led).
Further, removing the ‘noise’ of extrinsic causes from the data helped them focus on mortality caused by intrinsic – or gene-influenced- factors like age-related diseases, genetic mutations and the general decline of health with age. This allowed the genetic signals to shine through.
Why does this study matter?
This finding upends decades of research that assumed lifestyle played a larger role in determining lifespan. Traditionally, just about 25% of lifespan variation had been attributed to genetics.
It is also expected that these findings could give more impetus to large-scale research to identify longevity-associated gene variants and biological pathways that influence ageing.
What does this mean for our longevity goals?
The short answer: nothing changes.
Here’s why:
Firstly, you cannot change your DNA sequence – not yet at least. So, you are literally stuck with the genes that you were born with.
But, you also need to account for the ‘epigenome’ – which is the sum of all your genes and all the factors that regulates how these genes act.
When we choose to eat healthy or commit to a daily morning run or when we smoke and consume alcohol, epigenetic changes occur. These changes could turn your genes on or off without altering the base DNA. Thus, even if we are genetically prone to obesity, eating right and exercising regularly could help us keep our weight under control.
In short, lifestyle still counts. Even if you are dealt a bad hand by fate, you can make up for it through lifestyle changes. Which by the way, is also what this study says when it points out the 45% of lifespan is influenced by lifestyle.
In short, I would go so far as to say that the odds are really not that bad. It’s merely a case of ‘six of one and half a dozen of the other’.
One Small Thing
The case for investing in ‘healthspan’, not ‘lifespan’
No conversation on longevity is complete without discussing healthspan – or the number of years lived in good health, free of disability, frailty and serious chronic diseases.
Of course, this differs from lifespan which is essentially how long you will live. As we have already seen above, 55% of lifespan is determined by genetics. Plus, there is – as on date – no magic pill or procedure to extend lifespan.
But you can extend Healthspan.
You can choose to live healthier for the longer part of your life by making the right choices.
I, for one, would rather chase an attainable goal (healthspan extension), than a distant chimera (lifespan extension).
What will you choose – to be a fatalist or to act?
Speaking of genes, a study led by an Indian genetic testing firm had identified the presence of genetic variants for longevity in long-lived Indians in 2024. This includes the FOXO3 gene variant – a longevity marker found in centenarian populations in the Blue Zones.
Another interesting thing they found – people who were shorter were living longer.
Now I also got the opportunity then to interview Anuradha Acharya, the Founder & CEO of MapMyGenome, the company behind this research. Head here if you want to read or listen to that conversation.
Before You Go
Govt prepares for an India that could ‘‘grow older before it grows richer’
For decades, India has incentivised population control. Remember ‘Hum do, hamare do’? The latest report from the 16th Finance Commission signals the tide may be turning.
Now, the Union government, as you would know, distributes taxes collected among the states. Who gets how much is decided basis a complex formula that takes into account multiple factors (each have a specific weightage).
States’ success in population control termed ‘demographic performance’ has been a key factor for decades. The ones that demonstrated better population control got a bigger slice of the revenue pie.
However, in the report tabled last week, the Finance commission reduced the weightage for ‘demographic performance’ from 12.5% to 10%. This change reflects the growing concern that India could ‘get older before it gets richer’.
The commission notes that states in the South are already grappling with the fallout of a greying population and dipping fertility rates. It also signalled that low fertility rates or population control should not be a criteria for tax devolution anymore.
Another important change – the commission has introduced States’ contribution to GDP as a new criteria with a 10% weightage, signalling that economic efficiency and growth will be rewarded.
Our Takeaway:
This report comes on the back of the Budget proposals outlined last week that set about building the infrastructure for a greying population. It did this by funding drug development facilities, eldercare, mental health and emergency services.
The Budget proposals and the Commission report underline a subtle shift – India’s fiscal system is finally looking beyond the ‘youth dividend’. It is preparing to answer to the challenges of demographic transition, possible labour shortage and long-term growth.
And that should give us midlifers something to be optimistic about, right?
That’s it from me. Look out for that special edition that will drop in your inboxes at 5:35PM IST today.
Kavita Krishnan