If the allele frequency in a particular population is fixed, then the genetic contribution to ultimate IQ outcomes is fixed. Since heritability is a measure of the total genetic portion of the existing diversity within a population, the more non-genetic factors that contribute to diversity of outcomes that exist, the smaller the relative percentage genetic factors contribute, and thus the smaller the measured heritability will be. Thus stating all the non-genetic factors of an attribute that has been measured to be highly heritable only reinforces just how robust the effect of genetics is on the outcome.
This just demonstrates your ignorance of methodology yet again. Individual environmental factors need not be accounted for at all because environment is a complicated and abstract thing – it is everything that is not genetic. Consider the difference of IQ correlation between monozygotic and dizygotic twin pairs – .86 for MZ pairs and .60 for DZ pairs. The issue is that these correlations are the result of both genes and shared environment. It is the difference between them that can only be accounted for by genetics (or so the thinking has gone). So the MZ twins sharing 100% or their DNA rather than an average of 50% of their DNA resulted in an additional correlation of .26 with the same level of environment sharing. Thus the thinking was that if 50% of genetics accounts for .26 of the correlation then doubling that will get you the total heritability of .52, this is how a lot of those old studies arrived at 50% heritability, but anyone who understands how genes actually function will know that this is way too low, because sharing one allele at a particular locus only sometimes results in the same phenotype whereas sharing two alleles at the same locus almost always results in the same phenotype. The phenotypic similarity of MZ twins is actually much higher than twice that of the DZ twins, and so much more complicated calculations are needed.
A meta-analysis found the heritability of adult IQ to be about .85
http://cdp.sagepub.com/content/13/4/148
American Psychological Association states heritability of post-adolescent IQ to be .75
http://psycnet.apa.org/?&fa=main.doi...3-066X.51.2.77
This study found a heritability estimate of about .80
http://link.springer.com/article/10.1007%2FBF01067188
Not to mention that MZ twins raised separately still have the same IQ correlation, while the adult IQ of adoptive siblings correlate no more than the IQ of strangers.
Well the Flynn effect seems to be coming to a halt in developed countries (probably because there is a genetic range which limits the ultimate outcomes):
http://www.iapsych.com/iqmr/fe/Linke...asdale2008.pdf
Also many of the nurture over nature claims based on child IQ tests are pretty useless since environment can really effect how well children test, but ultimately the heritability of adult IQ is much more robust.
Then you haven’t been paying attention:
Genome-wide association studies establish that human intelligence is highly heritable and polygenic
That study seems to have confirmed that at least 40-51% of intelligence (you can see how that was defined) can be attributed to the 549,692 common SNPs they tested. Keep in mind that there are actually 10 million SNPs in the human genome, so their result is not inconsistent with the much higher statistical estimates of heritability (which geneticists also recognize and employ by the way).