The difference between living to 90 and living past 105 seems to depend largely on genes, according to a study of siblings.
For people who live to 90 years old, the chance of their siblings also reaching age 90 is relatively small—about 1.7 times greater than for the average person born around the same time.
But for people who survive to age 95, the chance of a sibling living to the same age is 3.5 times greater—and for those who live to 100, the chance of a sibling reaching the same age grows to about nine times greater.
At 105 years old, the chance that a sibling will attain the same age is 35 times greater than for people born around the same time—although the authors note that such extreme longevity among siblings is very rare.
“These much higher relative chances of survival likely reflect different and more potent genetic contributions to the rarity of survival being studied, and strongly suggest that survival to age 90 and survival to age 105 are dramatically different phenotypes or conditions, with very different underlying genetic influences,” the authors write in the study published online in the Journal of Gerontology: Biological Sciences.