SubscribeI think there's a lot to critcise about the article, but you have to admit that there is a taboo on discussing any sort of racial difference, more so than gender differenceYeah, right, it's so "taboo" that Murray has been able to sell millions of his "Bell Curve" book and received tons of press coverage for his theories: what a martyr, languishing in penniless obscurity!
There are plenty of statistical approaches scientists use to reliably disentangle the relative contributions of (a) genes, (b) shared environment (e.g., parental influences), and (c) non-shared (i.e., unique) environment to a particular trait. Typically these rely on twin or adoption samples. For example, the contribution of shared environment can be estimated by comparing the similarity between identical twins raised together to identical twins raised apart.Sure, except that these "reliable" statistical methods systematically underestimate the influence of environment in favor of "genetic" factors - even, no, especially the twin studies so beloved of the "scientists" you name.
It turns out, that for most aspects of personality and cognition, the variance is attributable about 50-50 to genetic and non-shared environmental causes. Familial environment has little or no detectable effect on personality or intelligence, counter-intuitive as it may seem.This is nonsense from start to finish. Do you realize that the concept of "heritability" as employed in population-genetics is extremely context-dependent?
Actually, that's incorrect.It's clear you didn't even bother to read the Ned Block essay, or if you did, you didn't understand it.
A more appropriate strategy would be to, say, compare black twin pairs in which one child was raised in a white household with black twins in which both were raised in black households, controlling for other relevant variables such as parental socioeconomic status.Again, if you'd actually bothered to read the Block essay I linked to, you'd realize why this would still lead you to an inflated estimate of the degree to which IQ is determined by "race", but you clearly didn't bother. If all red-headed children had their brains bashed in from childhood on because of some social stigma, would that mean that the gene for red-headedness "caused" retardation? According to the textbook definition of heredity, yes!
It's certainly context-dependent (see my previous post). But I think there's very little evidence to suggest it's 'extremely' context-dependent, unless you include highly atypical extremes.What you "think" and what is true are very different things; not only are there recent studies showing the heritability of IQ to be as low as 0.10 amongst poor Americans and as high as 0.72 amongst the rich - in perfect keeping with what we'd expect given the formula for heritability - but even a heritability figure of 1.0 for both groups would not imply that any difference in IQ which existed between them was genetic - read the second link I provided.
Well look, there are tacit assumptions behind every statement. If you'd like me to qualify my statement by saying "personality dimensions such as extraversion display about 50% heredity and almost no shared environmental influence across virtually all human populations they've been investigated in to date," I have no qualms about that.1 - We aren't talking about extraversion but IQ.
On the other hand, I think you're going too far in the opposite extreme."Think" what you want: the fact is that your claims display nothing more than a facile understanding of the subject you're discussing.
The fact that estimates of heredity are context-dependent does not make them worthless.Straw man: who ever said they were "worthless"? I specifically said that people who confidently claim that "heritability of X is Y" without any qualifiers are talking rubbish.
The fact of the matter is that there seems to be relatively little perturbation of the estimates as a function of culture.A blatantly false claim. Try getting that one over on someone less aware of the literature or the underlying mathematics than I am. Give me any varying trait you want, and I can easily put together a population group with the right parameters to hit any number I please. In fact, Eric Turkheimer's study blows to pieces what you're trying to pass off here as knowledge.
In fact, not only are the gross contributions of genetic/environmental roughly the same, but some groups of researchers have even replicated the same genetic structure of personality (i.e., the same patterns of covariance in traits) across multiple samplesUtter and total bollocks, backed up by nothing more than vague allusions to "some researchers", all conveniently unnamed. Not only is it factually impossible for anyone to claim to be able to give a definitive answer to such a thing as a matter of sheer logistics - who has the resources to examine all the ethnic groups, castes, clans and income strata on this planet of ours? - but any quack whatsoever can pick scores of subject groups to study which only differ by dialect and geographic location, and then claim that his or her work can stand in for humanity as a whole.
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We're all eeeeeeequal.
posted by uncanny hengeman at 1:40 AM on September 5, 2005