Don’t rely on ‘good genes’ for long life
If you think you’ll live a long life because your grandma made it to a grand old age, think again. A major new study suggests that genetics has only a small effect on longevity, reports CNN.com. Researchers analyzed anonymized data from more than 439 million people—including their birth years, death years, and family connections—from the genealogy site Ancestry.com. Initially, the results appeared to match the findings of previous studies. For siblings and first cousins, longevity heritability—how much of the differences in life spans can be explained by genetic variations—ranged from 15 to 30 percent.The data also showed that spouses often had similar life spans, possibly because couples share nongenetic factors such as diet and lifestyle. More surprisingly, siblings-in-law and first-cousinsin-law had similar life spans, despite being neither blood relatives nor housemates. Researchers believe this correlation is a result of “assortative mating.” Income, for example, can influence life span. So if people from families of similar income and social status marry each other, they would have similar longevity. When researchers factored assortative mating into their calculations, they found genes were responsible for no more than 7 percent of longevity. “Although there is a genetic component” to longevity, says co-author Cathy Ball, chief scientific officer at Ancestry, “this study shows that there is a major impact from many other forces in your life.”