Scientists have long believed that longevity is shaped by lifestyle choices; however, a new study reveals that genes may play a larger role in determining how long people live, reports BritPanorama.
Genetics accounts for over half of the differences in lifespan—two times higher than earlier estimates. The finding aligns with observations people often see in their family trees or hear during annual physicals.
“It’s not surprising at all,” said Dr. Deborah Kado, co-director of the Stanford Longevity Center, who was not involved in the study. While scientists generally agree that most traits have both nature and nurture components, lifespan was traditionally thought to be driven largely by environmental factors.
The study, published Thursday in the journal Science, suggests that longevity resembles other complex traits—such as cholesterol levels and osteoporosis risk—that are influenced by numerous genes but are also heavily shaped by lifestyle and environmental contexts.
Historical analyses underestimated genetic influences due to reliance on data from individuals born before the 19th century. These individuals typically succumbed to infectious diseases and accidents prior to the advent of vaccines, medications, and modern hygiene practices. The inclusion of these factors in older studies overshadowed the genetic influences on aging. Uri Alon, the lead author of the study, noted that by refining the data to exclude these factors, “genes shine out to their full effect.”
“People were thinking, ‘Oh, genes are probably irrelevant,’” Alon explained, emphasizing that there exists a genetically predetermined lifespan. However, he stressed that genes do not narrate the entire story.
People still have some control over their lifespan
Despite genetics accounting for 55% of lifespan, the remaining 45% is subject to factors within our control. “Some of it is luck, and some of it is our decision,” Alon stated.
According to Alon, lifestyle choices—such as exercise, diet, and social connections—can influence a person’s genetically determined age by approximately five years. “Genetics is not a done deal,” he said.
For instance, someone genetically predisposed to live to 80 years could reach 85 with healthy habits, whereas poor lifestyle choices could reduce that expectancy to 75. “But healthy habits won’t get you from 80 to 100 if your genetics are 80,” he warned.
Life expectancy in the United States reached a record high of 79 years in 2024, according to data released by the US Centers for Disease Control and Prevention. It had been on an upward trend for decades before dropping by nearly a year and a half amid the Covid-19 pandemic.
Consequently, Kado argues that products marketed to enhance longevity are not the solution; instead, a focus on exercise, diet, and social connections remains vital.
The genes that determine genetic potential
While some genes have been identified as protective or detrimental regarding aging, Kado points out that longevity is a far more intricate trait influenced by various genetic factors. “There isn’t any one gene,” she remarked, highlighting the complexity of the biology involved; many elements determining age remain unknown.
However, as scientists deepen their understanding of biological aging, new tools may emerge to target pathways that mitigate lifespan. “If you know the genes, you know the mechanism,” Alon stated. “And if you know the mechanism, you can intervene—you can make drugs.” This strategy could shift focus from treating individual diseases to addressing overarching aging mechanisms.
Yet, such advancements are still decades away. Genetic screening for conditions like bipolar disorder and kidney disease can reveal inherited risks, but no current test reliably predicts genetic age. Alon noted that developing such a tool would be pivotal for enhancing genetic lifespan.
What’s most important: health or age?
Dan Arking, an expert in aging at Johns Hopkins University, illuminated another significant discussion within the scientific community: how to balance the value of years lived in good health against total years lived. “If you can be healthier for longer, that to me has huge value,” he asserted, arguing that living to a greater age may be of little worth if those years are not spent in good health.
Arking highlighted that mitigating the risk of age-related diseases like osteoporosis can translate into more years spent in good health. However, extending life is more complicated, and it remains uncertain whether lifespan can be pushed beyond 122 years, the age of the oldest verified person.
“Once you get to a certain point, things just shut down,” he added, suggesting an upper limit may exist.
Alon also prioritizes quality of life over longevity, noting that while average life expectancy has doubled in the past 150 years, maximum lifespan has barely shifted. In fact, mortality rates among centenarians have not improved in the last 30 years.
“Once we come close to 100, we’re already feeling the wall of 120,” he explained, suggesting that significant advancements would necessitate drastic and possibly perilous measures.
Despite these ongoing discussions, Alon views the study as a promising step forward. He hopes it will rekindle interest in the genetic bases of longevity and propel further research. “Our study will be extra motivation to do those future genetic studies,” he said, affirming that both nature and nurture are essential in understanding longevity.
