I wouldn't do too well eating what a lot of my European ancestors were able to survive on once agriculture/farming became the norm. Likely lots of grains, tubers, stuff like that you could grow and store to avoid starving. I do well with meat and presently dairy, though, which I imagine they ate a lot of where they were from. I think the message to not eat processed junk is good whether one eats consistent with personal ancestral culture or not. I don't really know if eating things specific to one's known ancestry is important or not, other than obvious things like whether one can produce enzymes to break down lactose in dairy, which was a mutation common only to certain ethnic groups.