Is intelligence determined by genetics?
I keep seeing this idea posed in assorted E2 nodes, and I find the idea just a wee bit disturbing. I don't know if it originated with The Bell Curve or with Ayn Rand or what. And obviously, there's a lot of room for debate here, especially since it's hard to find a definition of what "Intelligence" really is.
Our own Webster 1913 defines it as "The act or state of knowing; the exercise of the understanding." But as Ariston pointed out, those two aren't really the same thing. Knowing something is quite different from understanding it; imagine the difference between memorizing a favorite poem and comprehending the poet's intended meaning.
Further, intelligence shouldn't be linked to one's sheer volume of factual knowledge. Intelligence seems to be one's ability to use facts, to solve problems a la Mensa's IQ tests. This is why Everything isn't intelligent: it can't independently use the facts stored in the database.
So, with that working definition: Is intelligence genetic? Do the chromosomes we are born with entirely determine the maximum IQ we're capable of?
In thinking about this, I drew a parallel to muscular strength. Most would agree that certain people are born with the potential for a larger physical build. But the key word there is potential -- that the person has an advantage to develop a better musculature. But that advantage still needs to be exploited through strength training, daily exercise, and so forth. The individual isn't born to be stronger -- they just have an easier time getting there than most.
Similarly, I imagine that some people have a genetic advantage toward developing a higher intelligence, but that it's only an advantage, a potential. Intelligence, the ability to work with knowledge to solve problems, isn't instinctive to anybody. Problem solving is something that can be learned, practiced, trained, and in that way improved. If some have a genetic advantage which makes it easier for them to develop intelligence, that's to be expected. But unschooled and unused, that advantage won't amount to much.
So please, let's stop this assertion that raw intelligence is something determined at birth. Claiming that someone was born to have no better than a 100-point IQ is as silly as claiming they were born to bench press no more than 120 lbs.