How Much Does DNA Really Influence Lifespan?
For a long time, scientists believed that DNA played a major role in determining lifespan. However, a joint study by Calico and the nonprofit Ancestry reveals that our personal choices might have an even greater impact.
It was once widely accepted that longevity was primarily dictated by genetics. Recent research, however, challenges this long-held belief.
In 2013, Google co-founder Larry Page announced the launch of Calico (short for California Life Company), a venture dedicated to tackling mortality. Since then, this longevity-focused lab has been probing fundamental biological questions about aging in hopes of eventually overcoming death. One of Calico's earliest hires was renowned geneticist Cynthia Kenyon, who two decades ago doubled the lifespan of a laboratory worm by altering just a single letter in its DNA.
Soon after, Kenyon brought on bioinformatics expert Graham Ruby. Rather than diving into worm genetics or studying colonies of long-lived naked mole rats, Ruby aimed to first quantify how much genes truly contribute to lifespan.
Previous researchers had explored this question but arrived at conflicting conclusions. To gain clarity, a much larger dataset was needed. Calico therefore partnered with Ancestry, the world’s largest genealogy database and a leader in consumer genetics.
Starting in 2015, the two organizations collaborated to investigate whether lifespan is inherited. Ruby sifted through vast genealogical records housed by Ancestry, analyzing the family histories of over 400 million individuals from Europe and America dating back to the 1800s.
While longevity often runs in families, the study found that DNA’s influence on lifespan is far less significant than previously thought.
According to Ruby, the heritability of lifespan is no greater than 7%, contrasting with earlier estimates ranging from 15% to 30%. What did Ruby uncover that others missed? He noticed a pattern contradicting the old saying that opposites attract.
It turns out that people tend to select partners with similar expected lifespans, a phenomenon known as assortative mating or non-random partner selection. This pattern extends beyond longevity to a range of genetic and sociocultural traits. For example, individuals commonly choose partners with comparable economic status and education levels.
Ruby’s insight came when he examined not just blood relatives but relatives by marriage.
Using the fundamental principle of inheritance—that each person receives half their DNA from each parent, passed down through generations—the researchers studied the relationships between pairs of individuals and their lifespans.
They analyzed parent-child pairs, siblings, and various cousin relationships without finding anything unusual. The surprises emerged when looking at relatives connected through marriage. Although one would expect little genetic similarity between spouses of siblings, the study found that people linked through marriage to close relatives had nearly the same likelihood of similar lifespans as blood relatives. "While no prior research had identified such an impact of assortative mating, it aligns well with how human communities are structured," Ruby explains.
These findings do not diminish earlier discoveries of specific genes related to aging and associated diseases. However, identifying additional such genes will be more challenging and will require vast amounts of statistical data. This is not an obstacle for Calico, which has access not only to extensive genealogical trees but also anonymized DNA data from millions of Ancestry customers.
The current conclusion is that individuals themselves have a greater influence on their lifespan than their genes do.
Factors shared within families—such as environment, culture, diet, education, and healthcare access—play a far more critical role than DNA.
Perhaps this is why Ancestry’s Chief Scientific Officer, Catherine Ball, notes that the company does not plan to emphasize longevity in its DNA testing products anytime soon.
"It appears that the length of a healthy life depends more on our personal choices today," Ball states. Statistical data highlight periods when lifespan declined sharply—among men during World War I and later in the mid-20th century for both sexes as smoking became widespread.
"My two pieces of advice: don't smoke and avoid war," she adds. And, of course, make time for regular exercise.
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