how "long"? Several studies have indicated (sorry, no sources) out that a person's diet during childhood affects the expressed genes of its offspring. There may

how "long"? Several studies have indicated (sorry, no sources) out that a person's diet during childhood affects the expressed genes of its offspring. There may be a generational lag (say, 20 years) between a change in diet and how it affects the population, it doesn't have to occur instantly.