"One thing they all have in common is that they survived a war which took 15% of the population of this country at the time" I think what you are hinting at he

"One thing they all have in common is that they survived a war which took 15% of the population of this country at the time" I think what you are hinting at here is that war was an artificial selection event that operated on and increased the prevalence of some trait related to longevity, say "robustness" or "ability to resist deprivation" or "quality". It is an hypothesis that could be tested, and one that is based on the theory that genes primarily determine longevity and not "lifestyle", as those years of food deprivation, physical and emotional trauma, rampant spread of diseases and general "bad times" could be very well be, according to a theory that sees "lifestyle" as the major factor in the observed variation of longevity, determinants of earlier, but post-war, deaths of the affected population.