Avoiding the vices of over-indulgence and idleness is no guarantee of reaching a ripe old age, a study has found.
Most people know an indestructible ancient relative who smokes, drinks and tucks into stodgy food with abandon.
Other less fortunate souls take scrupulous care of their health and still die young from heart disease or cancer.
The reason is that longevity may be programmed into the genes of certain lucky individuals.
New research suggests that nature is more important than lifestyle, or "nurture", when it comes to exceptionally long lifespans.
Scientists interviewed 477 Ashkenazi Jews between the ages of 95 and 112 who were enrolled into an ongoing study of longevity.
Ashkenazi Jews are descended from a small founder group and more genetically uniform than other populations.
The elderly participants, 75% of whom were women, were questioned about their lifestyle at age 70 - considered to be representative of how they had lived for most of their adult lives.
They answered questions about weight and height and provided information on alcohol consumption, smoking habits, physical activity and diet.
The results were compared with data from 3,164 people born around the same time as the centenarians who had taken part in a health and diet survey. The findings are published online in the Journal of the American Geriatrics Society.