And yet until the industrial revolution, environmental factors were the dominant effect. Anyone could have been taller with enough nutrition.

Genes are only ever expressed under certain environmntal conditions. The minimal condition for all of them is being alive. Malnourishment, or perhaps too much caffeine, amongst a hundred other things, all determine how our genes for height express themselves.

Which is all to say, people are wrong when they say height is mostly genetic. It may be true enough under current social conditions though. I think the same problem applies to calling intelligence "largely" genetic.

Not arguing your idea in general, but the caffeine example is probably a myth[1].

[1] https://www.nytimes.com/2005/10/18/health/the-claim-drinking...

This is always what's meant. Perhaps it should be said more often... but nobody doubts that we can grow a bonsai.

The interesting question is how much do different factors matter in our present environment (and again ideally one should specify, e.g. rich-country & above-poverty-line, not just 201X) and in environments we might reasonably hope to create.