Life Span as a Stochastic Result
From Ouroboros, a look at the way in which the relationship between your genes and their effect on your life span is both a little random and a little determined: "[I]n humans only about 25% of the variation in life span can be ascribed to genetic factors to any degree, and even in lab animals where variables can be greatly reduced, only 10-40% of the life span variation has a genetic component. ... Life is like a long dice game, and while starting with a good endowment might let you keep playing for a longer time, eventually everyone craps out, and a run of bad luck can wipe out even the richest starting position rapidly. In between these extremes of genetic predetermination and pure luck, though, a recent paper in Nature Genetics finds another possibility: factors in the organism that are not heritable, yet from an early age can be reasonably good predictors of mortality." It's all very interesting - but you shouldn't forget that the real determination of your healthy life span will be made by the efforts of you and those you band with to support the development of working anti-aging medicine.
Link: http://ouroboros.wordpress.com/2007/01/10/stochastic-effects-in-lifespan-determination/