There's a theory that different blood types (because of heredity linkage) have different nutritional needs. While I think it is a little simplistic, it does make a lot of sense to think that cs's jolly Italian ancestors would have had more babies eating pizza and thereby have given him more pizza genes. Similarly, if grandma was an Eskimo thriving on blubber then I'm gonna be healthier on a high fat diet. Darwinianism can be abused like anything else, but the big idea that healthy individuals leave more babies is a no-brainer.

I thrive on red meat. Heck, I started salivating just typing the darned sentence! Some do well with milk. Others had ancestors who did not keep herds. Same with grains.

As if things weren't complicated enough. -Rick