But in fact the correlation of longevity between individual parents and children is very low. For the people dying in England in the period 1858-2012 with the rare surnames used in chapter 4, we can measure the correlation of longevity between fathers and sons for more than four thousand sons surviving until at least age 21. That correlation is only 0.13. If we take the average of both parents’ ages at death, that correlation increases to 0.26. But it is still low. In reality, your age at death is not strongly predictable from your parents’ age at death. All those saving more for retirement simply because both parents are fit, healthy, and in their nineties should stop immediately. Your expected additional longevity relative to the average is only three years.
That is from Greg Clark’s new and noteworthy The Son Also Rises: Surnames and the History of Social Mobility. Here is Kevin Drum on the book.