Genetics may determine over half your lifespan—but habits still matter

A new study has shown that genetics plays a far bigger role in lifespan than previously thought. Researchers now estimate that over half of the differences in how long people live come from their genes. But lifestyle and environment still have a strong influence—enough to shift a person's expected age by roughly five years.

Earlier research often underestimated the impact of genetics on longevity. This happened because older studies relied on data from people born before the 19th century, when living conditions were much harsher. When modern factors were included, the genetic influence became harder to see.

The latest findings suggest that while genes set a baseline, choices like diet, exercise, and healthcare can still alter a person's lifespan. For example, life expectancy in the United States hit a record high of 79 years in 2024, reflecting improvements in public health and medicine. Yet the study also highlights a key debate: should scientists focus on extending total years lived or improving the number of healthy years?

One major question remains unanswered. No one knows if humans can live beyond 122 years—the oldest age ever recorded. The research may also inspire future studies on how to target specific genetic pathways that shorten life.

Currently, no test can reliably predict a person's genetic age. But the study's authors hope their work will lead to tools that help identify and address factors that cut life short.

The research reaffirms that longevity depends on a mix of genes, environment, and personal habits. While genetics account for 55% of lifespan differences, healthy choices can still add years. Scientists now have a clearer picture of how these elements interact—but extending life beyond current limits remains uncertain.