I find this notion rather peculiar. Do people get "highly turned off" that they can't "get tall"? I've known for my entire life that I could never become a professional athlete -- I simply don't have the physique.
What is it about intelligence which makes people get so much more upset than they get about physical attributes?
My guess is that "intelligence" can be largely hidden, whereas your physique is immediately apparent even if you just sit and do nothing. That it is hidden then, gives it a mysterious feeling of potential, and nobody wants that put in a box. I think it is a cultural phenomenon that necessitates something like unconditional encouragement.
Would you rather be a brain without a body or a body without a brain?
For a heartrending story about the role intelligence plays in shaping personality, read Flowers for Algernon by Daniel Keyes.
My claim is even slightly deeper/more provocative than that - I don't think that efforts by a lot of academics (including a lot of my friends) to propagate an idea of "general intelligence" which solidifies at a young age are entirely benign. I think that they are largely founded in worry and attempts to create an elite academic class. Once you're in, you're in (since getting in means that you have a "good" brain which is not really subject to change). It's self-reinforcing and (in my experience) always based in self-doubt.
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As an aside, the idea that "people get so much more upset" about the intellectual than the physical is completely absurd. I know a ton of people (girls and guys) who freak out constantly about their appearance. I know like 3 guys (including myself) who are the least bit worried about our intellects. Admittedly, most of my friends are academics, but my interactions with people outside this sphere indicate that the trend is not peculiar to my social group (and is probably even more physical-attribute oriented, in general). Seriously, I can't believe that you wrote this. This isn't meant to be mean or like ad hominem - but seriously? Do you actually believe what you wrote? Do you know anyone who isn't an academic?
To answer what I think you might have meant (namely: why do _I_ get much more freaked out about my intelligence than my physical attributes - which is also presumptuous because you have -no- idea how much I care about my physical attributes) I would like to observe that in modern western society "we are our minds." Your mind is essentially the limit of your capabilities in the sort of world I'm sure both you and I live in (the quote unquote information world). The mind is connected with the ability to create beauty (art), the ability to connect with other human beings (sex), the ability to experience spirituality (love), etc. In the academic world, at least, our physical bodies are a burden. They wear out. They get cancer. They die.
Did you seriously ask this? Were you being rhetorical? I can't tell. I don't mean to be mean, but sheesh.
(1) and I accuse you of attempting to employ an underhanding rhetorical trick in making this implicit comparison, I might add.
DNA, Diet, and Stimulus.
DNA limits what structures can develop which is the basic foundation of intelligence.
Diet provides the raw materials to crate the structures that DNA is trying to build. Poor diet causes DNA to sacrifice specific objectives to insure survival. Specific toxins like lead also limit the body's ability to create structures. At the same time short term diet inhibits performance.
Experience refines specific structural elements. Without early experience in specific areas it becomes harder to develop efficient systems for dealing with those situations. It's not impossible to learn French at 50 if you only know Spanish, but it's far easer to learn it at 5 than 50. Part of this has to due with the brain ignoring sounds that it finds unimportant.
All of the above statements are well supported by a huge body of research being annoyed by them is like getting pissed off at gravity while building rockets.