OK, these are serious questions. 1) This is true, and uncontroversial. Nobody doubts that bonsai are small for environmental reasons. More technically, the her

OK, these are serious questions. 1) This is true, and uncontroversial. Nobody doubts that bonsai are small for environmental reasons. More technically, the heritability of traits is inversely related to how variable the environment is. Once everyone is well-fed & well-cared-for, you expect higher correlations between parents' height and children's, compared to the earlier world where many were stunted. (And likewise you expect a stronger influence of people's innate interests on what jobs they do, once they are rich enough to turn down better-paying alternatives which they hate.) 2) This is a real concern, but it also depends a little bit on what you hope to achieve. My extreme example: If a freak accident on the way home from the 1964 olympics had stranded the Dutch men's & woman's gymnastics teams on the same island as (m&f) Nigerian basketball teams, and you visited today, then in this population genes for blue eyes would be a pretty strong predictor of being short. Because they would mark ancestry, not because of a more direct link. This may not be a terrible thing. If what you want is a test to see who is more susceptible to some illness, for the purpose of giving them screening from age 40 instead of 50, then if what you are detecting is ancestry-markers not heart-muscle-genes, do you care? But for other purposes you may really want to know the functional genes related. One thing you can do is to look only at differences in height (etc) between siblings, who by definition have the same ancestry. This is also done, but it's harder to collect this data, so studies for humans are smaller & noisier. But for plants you can do this very well, control everything. And I think that for dairy cows this is done very well (you know their ancestry perfectly, so the only point of DNA testing is to get information which that doesn't capture).