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(CNN) – Do you think that you will stay long because grandmother lived until a late age? Not so fast: Genetics has only a minor impact on longevity, according to a new study involving more than 400 million people. Longevity is mainly determined by lifestyle, with less than 10% of DNA, according to the study published Tuesday in the journal Genetics.
"We know that people who are looking for their family are very interested in the subject of longevity," said Cathy Ball, co-author of the study and scientific leader at Ancestry, a consumer genetics company that provides an online resource for family history.
To what extent do our genes contribute to our lifespan?
Studies suggest that genetic differences account for only 15% to 30% of longevity, and that it is the non-genetic differences between us, such as the way we eat and if we have a fatal accident, that explain why a person has had a longer life. than another.
Scientists at Calico Life Sciences LLC, a company specializing in the biology of aging, funded by Google, have teamed up with Ancestry researchers to study the genetic influence on lifespan. They analyzed anonymous family tree structures – or "genealogies" – including the year of birth, the year of death, the place of birth and the family ties for 439,361,203 people. These family trees or public family trees were generated by Ancestry subscribers.
The size and scope of the database allowed Calico's scientists to "scan families from generation to generation, analyzing the longevity of not only family members but also step-parents," Ball wrote. in an email.
Using mathematical and statistical calculations, the team found that for siblings and first cousins, the heritability to longevity – or the magnitude of the variation in the lifespan of people who may be attributed to genetic variation – was about the same as in previous studies. Specifically, genes accounted for between 20% and 30% of longevity, with this estimate falling below 15% for opposite-sex family relationships.
The researchers also found that spouses had a similar life span longer than siblings of the opposite sex. One possible explanation is that spouses live in the same household and thus share important non-genetic factors, such as diet and lifestyle in general.
However, the results of the study also showed that the brothers-in-law and the cousins had a similar lifespan, even though they were not related by blood and did not did not share a living space.
What would explain this discovery? The authors think that a likely explanation is "assortative mating".
"Assorttive mating is a mating pattern in which individuals with similar phenotypes mate more frequently than was expected with a random mating pattern," wrote J. Graham Ruby, lead author of the mating pattern. study in an email.
Obviously, no one knows when their potential partner or they will die. In this case, the matching mating would be based on secondary characters. For example, we know that income influences the life span because eating well and taking care of one's health are both somewhat related to money. The study suggests that if people from equal-income families tend to marry, this would explain similar longevity in non-family relationships.
The researchers estimated that heritability did not account for more than 7% of longevity, perhaps even less, taking into account the choice of mating in their calculations.
Your genes alone can not save you from an untimely death.
Genetic contributions to longevity
The new research adds to "existing clues to what drives aging," said David Melzer, professor of epidemiology and public health at the Faculty of Medicine at the University of Exeter in the United Kingdom. United and Professor at the Center on Aging of the University of Connecticut Health. Center in the United States.
Melzer, who was not involved in the study, wrote in an e-mail that "it would have been nice to see" estimates of heritability in case of exceptional longevity because the centenarians would have a degree heritability higher than the others.
Melzer and Luke C. Pilling, a researcher in genomic epidemiology at the Exeter University School of Medicine, have also studied the genetics underlying longevity.
"Our own recent estimate of the inheritance of parental longevity directly from the common gene variants present in 75,000 Britons was 8.47%", implying a "total heritability of life" of 10 to 20%, explained Melzer. This is "significantly higher" than the 7% or less suggested by the new family tree study, he said.
He noted that more than 20 genes have been identified for longevity.
"These include genes that interact with health-related behaviors, such as the nicotine receptor gene," said Melzer. He and his colleagues have also discovered genes that influence cellular senescence or the deterioration of individual cells. "It is likely that many variants of these genes are involved in life and aging," he said.
In the end, Ball said, "While there is a genetic component, this study shows that there is a major impact of many other forces in your life."
The results suggest that anyone who wants a long life would do better eating and exercising, rather than relying on good genes from grandfather.
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