Family trees of 400 million show that genetics has little influence on longevity

Eyes and hair colour, a widow’s peak at the base of one’s hairline, the ability to curl your tongue and the likelihood of having diabetes or high cholesterol — a few of the things you can inherit from your parents through DNA. There are unproven claims that inherited genes could even influence perception and shape personalities. While evidence for it may still be several studies away, there’s no debate about the important role genes plays in shaping metabolism and body function. It would also make intuitive sense to assume that genes and longevity, too, are closely linked. A new study of more than 400 million people offers evidence to the contrary. The biggest factor that affects lifespan — lifestyle — is hardly (~10 percent) affected by a person’s genetic makeup, the study says. Researchers from Ancestory.com collaborated with scientists from Calico Life Sciences to explore how closely (if at all) a person’s lifespan and genes are linked. [caption id=“attachment_5526321” align=“alignnone” width=“1280”] Representational image. Image courtesy: Fotozone[/caption] Family trees (also called ‘pedigree’ charts in genealogy) of close to 450 million people were studied for the dates of births, deaths, places of births and connections to other members in their family. A statistical analysis of all these parameters revealed that longevity and genes were linked in less than 20-30 percent for cases in same-gender relatives and 15 percent for relatives of different genders. Interestingly, the study found some unexpected patterns as well. For instance, longevity in spouses was very similar — more so than siblings. [caption id=“attachment_5526381” align=“alignnone” width=“1280”] Couples in the study have similar lifespans.[/caption] Another fascinating pattern found that the lifespans of siblings-in-law or first-cousins are also fairly similar, without sharing genes or a home for that matter. This, the researchers attributed to a process of ‘assortative mating”. “What assortative mating means here is that the factors that are important for life span tend to be very similar between mates,” Graham Ruby, lead author from Calico Life Sciences, said in a statement. This would also mean that people tend to choose mates with similar traits to their own — from which lifespan may be an unintentional one. All factors considered, the authors found that hereditary genes affected less than 7% of the average person’s lifespan. “Though there is a genetic component, this study shows that there is a major impact from many other forces in your life,” Cathy Ball, co-author of the study and chief scientific officer at Ancestry.com  told CNN. The study was published in the journal Genetics.