Human lifespan is also determined in part by genetic factors. The heritability of human longevity is estimated as approximately 25% [14]. This estimate is also supported by a study of the entire population of Iceland [15]. In addition, it was shown that siblings of centenarians have a 4-fold greater probability of surviving to the age of 91 [16]. A study of families with long-lived siblings localized a longevity locus to a region on chromosome 4 [17], [18].
