Steve’s Barking; Diet DNA

Are we killing ourselves by going on fad diets. We have he Mediterranean diet. Perhaps that works great for those who live by the Mediterranean Sea, with centuries of digesting that kind of food.
Perhaps it would not prolong life and maybe even shorten it if one is an Eastern European.
A vegan diet my be good if one has the DNA of people who had very little chance to eat flesh, and perhaps the opposite is true meat would be bad for the digestive system in a high protein diet with lots of meat if your ancestors ate mostly vegetables and fruit.
Perhaps one is disposed to be heavy in cold climates to keep warm, and thinner in warm climate if ones DNA comes from a hotter climate.
Do diets have a negative impact without knowing ones DNA?