Most people on HN are 1-3 sigmas on the right side of the IQ bell curve. They have a hard time understanding what life is like on the other side (although rampant off-shoring and H1B wage gouging might, one day, engender some horizon broadening).
It's just a question of degree. Is height solely determined by genetics? No - we know that nutrition plays a large part. But potential height is still dominated by genetics. It doesn't matter whether or not he eats his Wheaties, the average kid is not going to grow up to be Shaq, period.
Ditto for intelligence. Things like iodine and breast feeding seem to be capable of boosting IQ by a few points each. Doubtless there are other factors. And yet, there is little reason to doubt that there is a genetic ceiling to any given person's potential IQ, at least if you accept that IQ stems from physical properties - in which case, how could it be exempt from genetic determination?
This is reality, and there is little hope of improving the lot of those who did not win the genetic lottery without first accepting that there is, in fact, such a lottery.
Just a precision. I see two questions of interest when talking about whether height and IQ come from genetic or environmental factors.
The first question is, how much of the currently observed variability in height (and IQ) is explained by genetic factors and environmental factors respectively? Meaning, how much of a lottery genes actually are?
The second question is, how could we take control of the variability? Meaning, how much could we deliberately influence height (and IQ) through genes and environment respectively?
By itself, the first question is of high academic interest, and low practical interest. The second question is just the opposite. But more important, those two questions should be treated separately, so everyone knows what we are talking about.
Read this: http://www.isteve.com/How_to_Help_the_Left_Half_of_the_Bell_...