Quote:
Originally posted by aeon@Aug 30 2003, 06:32 PM
Even with identical twins the differentiation in "IQ" varies 15-20% from those reared together as those apart - and that's those reared apart in similar socio economic situations. That % increases in correlation to significant differences in culture/class etc.,
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What's important though is not the difference between the twins but the similarity. Sure, the correlation scores for the IQ scores of twins separated at birth is about .2 difference but what does that matter in the question of whether there are genetic factors in the first place?
Since twins reared apart correlate at better than .70 and unrelated children reared together (adopted) only correlate .3 or so that's saying there IS a large genetic component.
What many in the field are saying today is that IQ is about .5 heritable.
Once we accept there is a genetic component of IQ and accept that IQ measures anything we might all call "intelligence" (that might be dubious and certainly challengable) we can draw another conclusion. Equal opportunities and continued equalization of people's intellectual environment will magnify the advantage of the genetically endowed.
If we naively assume that intelligence is at present 50/50 environmental/genetic (how convenient!) and our goal is to continually create a more educationally egalitarian society, then we will maybe someday reach a point where everyone's intellectual environment can be said to be more or less equal. At such a point, the 50/50 score we used to have changes to something like 80/20 in favor of genetic. Why? Because we are measuring difference between individual people. If every child has the same opportunity the children with natural advantages - and even small advantages will become comparatively important - will excel.
Last edited by Colin at Sep 1 2003, 01:24 PM