The example of the German monozygotic twins Otto and Ewald, both well nourished but sportsmen who pursued different sports, show that physique is exquisitely sensitive to environmental influences even between two individuals who share a genome and a prenatal environment in the same mother's womb. Take a look at the photos.
AFTER EDIT: I'm asked in a reply below what my point was, and it's partly to point out that the term "heritable" means something far, far different from "determined by genes." There are whole books
by professional geneticists, medical doctors, and psychologists patiently refuting the confusion in most popular literature about what "heritability" means, but the main point in this thread is that Shalizi is correct, and many psychologists are wrong, about what heritability figures mean in relation to IQ.
http://www.marksdailyapple.com/control-gene-expression/
http://www.joebower.org/2010/05/we-inherit-and-we-also-becom...
AFTER EDIT: I'm asked in a reply below what my point was, and it's partly to point out that the term "heritable" means something far, far different from "determined by genes." There are whole books
http://www.amazon.com/Nature-Nurture-Environmental-Influence...
http://www.amazon.com/Genes-Behavior-Nature-Nurture-Interpla...
http://www.amazon.com/Dependent-Gene-Fallacy-Nature-Nurture/...
by professional geneticists, medical doctors, and psychologists patiently refuting the confusion in most popular literature about what "heritability" means, but the main point in this thread is that Shalizi is correct, and many psychologists are wrong, about what heritability figures mean in relation to IQ.