Do Parents Affect How Long You Live?
By Bryan Caplan
Parents – especially moms – spend a lot of time nagging their kids to eat right, get some fresh air and exercise, not smoke, etc. If nagging changed behavior, and there is some validity to popular perceptions about “what’s healthy,” then parenting should affect life expectancy. Does it?
According to the literature I’ve tracked down, the answer is no. When you analyze life expectancy and mortality using twin studies, you get the standard behavioral genetic answer: genes aren’t everything, but parents still don’t matter. A couple of relevant studies:
“The Heritability of Human Longevity,” (Human Genetics 1996) looks at about 3000 Danish twin pairs. It gets a heritability estimate for life expectancy of about 25%, with non-shared environment getting the remaining 75%.
“Half of the Variation in Susceptibility to Mortality is Genetic” (Behavior Genetics 1999) looks at about 9000 Swedish twins. It gets a heritability estimate for mortality of about 50%, with non-shared environment getting the rest.
And here‘s a readable survey piece published in Nature in 2006.
At least in my experience, most parents claim that their nagging has long-run health benefits. “It may seem OK to eat ding dongs and play videogames all day when you’re ten, but you’re building bad health habits that will haunt you later in life.” Once again, though, it looks like parents overestimate their influence. If the short-run benefits of health nagging aren’t enough to justify it, it turns out that you might as well just hold your tongue.