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.Genetics accounts for over half of differences in lifespan — two times higher than earlier estimates. Still, the finding may resonate with what people see on their family trees or what they hear during their annual physical.“It’s not surprising at all,” said Dr. Deborah Kado, a co-director of the Stanford Longevity Center, who was not involved in the study. While scientists agree that most traits have a nature and nurture component, lifespan was thought to be driven largely by environment.AdvertisementAdvertisementAdvertisementThe finding, published Thursday in the journal Science, suggests that longevity is akin to other complex traits — such as cholesterol levels and osteoporosis risk — that are thought to be shaped by many genes but also heavily influenced by how and where people live.Previous studies underestimated the influence of genetics because they relied on data from people born before the 19th century. These individuals typically died of infectious diseases and accidents before vaccines, medications, modern-day hygiene practices and safety regulations became widely available.When these factors were included in older studies, they overshadowed genetic factors influencing age. Uri Alon, the lead author of the study, explains that by cleaning up the data to exclude these factors, “genes shine out to their full effect.”“People were thinking, ‘Oh, genes are probably irrelevant,’” said Alon, who studies lifespan at the Weizmann Institute of Science in Israel. “But we have a genetic lifespan kind of predetermined in our genes.” Genes, though, don’t tell the whole story.People still have some control over their lifespanAlthough 55% of a lifespan is set, the remaining 45% is up in the air. “Some of it is luck, and some of it is our decision,” Alon explained.AdvertisementAdvertisementAdvertisementAccording to Alon, those lifestyle choices — like exercise, diet and social connection — can shift a person’s genetically influenced age by about five years. “Genetics is not a done deal.”Someone genetically predetermined to live 80 years could reach 85 with healthy habits, while unhealthy lifestyle choices can shorten that expectancy to 75.“But healthy habits won’t get you from 80 to 100 if your genetics are 80,” he said.Life expectancy in the United States reach …
