there is a sort of concept that states "you are your biome", and no end of evidence to show that poor gut and other flora causes disease, with many ways to get there, diet bieng one there are many tribal groups that fair exceptionaly poorly on modern wester diets, with well documented cases of plains indians haveing spontainious remission of diabetes when going to the much leaner diet of there ancestors. this ties in with another sort of concept that there are no true racial or tribal differences, but there are enzymatic adaptations in population groups that are tied to environments and food sources that tend to get inherited, the upshot for many modern people is that it's a semi random crap shoot, as there are prople who go ahead and outlive all of there peers, and do whatever they feel like, smoking ,drinking, junk food eating octogenarians, not many, but some