i have trouble seeing how these comments apply to the content of the post - parenting influences are largely controlled (as you seem to indicate) and I don't see how these heritability estimates could reflect something unrelated to executive function. that's the whole point, they clearly have something to do with executive function. one would assume that something like appearance would show large unshared environment since kids dress differently, etc/
The short version is: think about how heritable something like "number of arms" would appear in a study like this. It would appear that variance in arm count is 100% environmental, since the only people who don't have two arms lost one in an accident of some kind. Arm count is therefore not controlled by genes!
for one simple example, it could be facial appearance. say that all parents in our culture react in different ways to different facial appearances. then the gene that is causing heritable executive function could actually be for the face that causes best parenting treatment.
any causations of this type (gene causes something detectable by parent, and parental reaction causes improved executive function) is consistent with the study/data.
i see - so you're talking about gene x environment interactions. it's true this isn't accounted for in the analysis.
but i find it hard to believe that environmental effects of any sort could explain 99% of the variance that we see here, and I don't know how even a whole genome analysis could rule out GxE interactions. how exactly is that done?
as far as i know, no one has done it or has a good way to. all the studies like this suffer from this problem. i think the researchers should be a lot more careful with what they say their study shows or not.
what can be done is to use arguments to determine which explanation is better.
i think the most important argument is this one:
we can explain how culture/memes (triggered by some detectable but unimportant effect of genes) would be able to affect intelligence, cause ADHD, and many other things. that is not a problem.
no one has a good explanation of how genes have complex and lasting effects on human minds and personalities.
of course for both points further elaboration is needed. but anyway, no one has made a strong case the other way.
interesting discussion. but regarding 99%, I know of no environmental manipulation which can explain that much of individual differences. it's not just about reliability, it's also about explaining all the variance - two different things.
if the memes cause effects in the presence of certain trivial traits caused by genes then that issue is solved, isn't it? the genes work as predictors like the study thinks, but don't actually do much of anything.
