Longevity is poorly inherited

Hereditary factors determine life expectancy by only 7%.

Kirill Stasevich, "Science and Life"

Life expectancy depends on genes: if a person has one of his parents or even both of them lived for a long time, then he himself has a chance of a long life; if one or both parents did not differ in longevity, then their descendants are more likely to pass away relatively early. On the other hand, life expectancy depends on a variety of extragenetic conditions: bad habits, stress, etc. How are hereditary and non-hereditary factors combined? For quite a long time it was believed that heredity here accounts for from 15% to 30% – that is, if we take the spread in duration among people, then exactly such a 15-30% share of the diversity of life terms will be due to heredity.

However, as researchers from the biotech company Calico LLC and Ancestry write in Genetics, the figure of 15-30% is greatly overstated. With the help of Ancestry data, which specializes in finding out pedigrees and building family trees, the authors of the article analyzed the pedigrees of more than 400 million people. Of course, specific names and personal data remained a secret, researchers were only interested in how life expectancy correlated with family ties. It turned out that if we take any family separately, then the life span in it will differ from the average duration in the population. And at first glance it seems that heredity really determines 20-30% of life expectancy.

However, in every family there are relatives who are not related by blood – for example, brothers and sisters of the wife and brothers and sisters of the husband. After all, there is no blood relationship between husband and wife either, unless they come from the same large family. And when they began to compare the life expectancy between different relatives within the same family, it turned out, as the portal writes The Scientist that there are more similarities between husband and wife here than, for example, between one of the spouses and his or her siblings. That is, a husband and wife are more likely to live the same length of time than a husband and his brother or sister.

Moreover, non-blood relatives in general were more similar to each other in terms of life expectancy than blood relatives, that is, the wife's relatives were more likely to live as long as the husband's relatives. And taking into account this correction for blood-necrovity, it turned out that hereditary factors determine life expectancy by only 7%. (For the sake of greater accuracy, the title should also be corrected: not only a long, but also a short life is also poorly inherited.)

But what is the reason for the similarity in longevity (or non-longevity) between husbands and wives? Here, most likely, it's all about the so-called assorted, or non-random crossing. A person, like many other animals, when choosing a mating partner, evaluates him or her according to a variety of signs. Often these signs are exactly the same as those of the chooser himself: despite all the fairy tales about cinderellas, in reality people pick up a couple from their own circle, with a similar level of education, the same social status. But if two people were born and grew up in similar conditions, then they will probably be similar in terms of life expectancy.

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