Researchers have spent a great deal of effort looking for genetic determinants of longevity in long-lived families. Elsewhere, initiatives searching large national databases for genetic determinants of longevity have turned up increasing evidence for genetic variations to play very little role in human life span. The pendulum is swinging towards the idea that the specifics of culture within human lineages are largely responsible for differences in longevity: who stays thin; who exercises; who maintains beneficial dietary habits; who has a lesser early life exposure to persistent pathogens; and so forth.
What makes some people predisposed to live and remain healthy much longer than others? That some persons reach an exceptional age has been recorded throughout history. It's tempting to write down such outliers as only the result of environment and behavior: for example, better-than-average nutrition, medical care, childcare practices, and hygiene, not to mention luck. But as average life expectancy continues to increase worldwide due to overall improvements in these and other factors, it's becoming clear that exceptional longevity and healthy aging tends to run in families. This suggests that genetic differences also play a role in assuring lifespan and life-long good health.
The Long Life Family Study (LLFS) focuses on families in the US and Denmark with multiple exceptionally long-lived members. It identifies, across two generations, which genetic, epigenetic, and other biological processes are associated with long life and healthy aging. Researchers now show that children born in exceptionally long-lived families differ from peers in their blood levels of biomarkers affecting the risk of type II diabetes: their genetic and epigenetic make-up help their body to remain responsive to insulin, even in old age. Their spouses - typically not born to exceptionally long-lived parents - tend to share these health- and lifespan-boosting biomarker levels. This implies that such family-specific beneficial biomarker levels aren't always inherited - you might also develop them if married to the right partner.
Among the children and their spouses, respectively 3.7% and 3.8% developed type II diabetes over the course of the study. This corresponds to a rate of 4.6 to 4.7 new cases of type II diabetes per 1000 person-years, about 53% lower than the rate among people between 45 and 64 years in the general US population. This implies that both the children and their spouses had a reduced risk of developing type II diabetes: one of the health and longevity benefits of being part of a long-lived family, either through descent or marriage.