You seem to believe that we don't know that, demonstrating precisely what we are talking about.

Nobody ever said that this is a guaranteed thing, and that's completely beside the point. Most things in life are not 100% certain, but we work with "highly probable" or "lots more chance" all the time. Using high quality ingredients doesn't guarantee a good cake, but if you don't start there, your chances of having a good cake are much lower.

You keep repeating that as if you know something special that others don't, but how it looks to me is that you are the one lacking the depth to understand the original argument.

One thing I don't understand is the argument you're trying to make here. A condition being heritable doesn't make it 51% likely to be genetically determined. For instance, people's environments are heritable, so the "heritability" of "IQ" doesn't say anything about how society should deal with the distribution of ability. It doesn't say we should allocate resources to improving ability and it doesn't not say that. It literally begs the question. Given that: what do you take the parent comment to mean?

So far as I can tell, we've never spoken before, so I'm not sure I follow the "repeating" thing, either.

The repeating part is about you saying basically the same thing to the previous commenter, I don't get how you do not intuitively understand that?

It's not exactly clear to me what you are asking but you seem to be making the traditional nature vs nurture argument, and you seem to think the environment is important enough to impact the IQ of an individual and more largely its abilities.

It's not clear what you mean by people's "environments are heritable" but from my point of view it was barely true in another era but nowadays with increased mobility it is just not true. Most people are very likely to have kids in a very different environment than they grew up in. And that is the case for 4 generations now, so I don't think there is any heritability there appart for a few privileged rich, I guess (then again, they have largely been replaced in the last century or two).

I have to say, I don't understand where you are going because we have a number of twin studies that clearly show that the environmental impact is not very large, at least for a single generation. There are also plenty of various fields, related to animals or plants that directly work with genetics, to change stuff regardless of the environment. GMO would not be viable if genetics weren't more important than environnement... I do think environment plays a role and is important for the very long term. But on the human scale, it takes multiple generations to have a significant change in the average so compared to the outsized influence of the base genetic material.

With everything we know about genetics, while there is no guarantee, children are largely a mix of their parents' traits, including intelligence. The higher the parents' intelligence, the higher the chance of this intelligence showing up more in the children (because intelligence is not localized at a single place in the ADN, but is spread out all other). I really don't understand people contesting that kind of thing, since it never bothers anyone when historically tall people, make, you guess it, taller people than the average. How surprising!

When it comes to the allocation of ressource, it is pretty simple: the humans who get more ressource thrive better, are allowed much more influence on the environment directly and indirectly wich can have large impact. It is not a hard argument to make that to benefit society the most, you want those ressource to go to the smartest humans available. If you do not, you dilute your benefits and may actually prevent those individuals from taking over because of poor ressource distribution. In the long term your society ends up dumber and worse off. This is basically where we are and exactly why society is getting restless in some places, it is not a tenable situation in the long term, because even though it may not look like at first glance, everyone is guaranteed to be worse off over time.

I don't know what previous commenter you're referring to.

I worry that you're confusing heritability with genetic determination, failing to account for the ways in which environments are inherited along with genetics, tacitly claiming that IQ is fixed at birth by genetics, ignoring epigenetics, and, of course, working under the assumption that IQ testing is statistically meaningful to the point where the kinds of comparisons you're trying to make are valid.

Your argument seems to condense down to "tall people have tall kids, so smart people have smart kids, so any demographic IQ pattern we see must primarily be fixed by genetics". That argument --- I'm paraphrasing it and apologize to the extent it doesn't capture what you're saying --- is weak in a bunch of places that you're not acknowledging, let alone rebutting. But more importantly, it's not a scientific argument; it's just a subjective, intuitive claim. Your intuitions are different from mine.

I don't know what previous commenter you're referring to.

You wrote this, to the parent I replied to.

  tptacek 14 days ago | parent | prev | next [–]

  Every time someone here mentions the heritability of IQ, I 
  wonder what they think that term means, because it clearly 
  does not mean what most people  intuitively think it does.

The "issue" you are talking about has already been addressed ; it is not something that has an effect large enough to be relevant, at least for a small number of generations. We could talk about the very long-term effects, and the necessity of territory/environment control but that's an even more politically loaded subject and it doesn't change what I say. You seemed even more confused about probability than you think I am about genetics, even if you lack that intuition, it does not make its effect go away.

Then again, since you seemd to have "forgotten" a previous comment of yours, I am inclined to think that you are either arguing in bad faith or don't really understand what you are saying. I would be happy to argue those things with a trained geneticist but since my argument is probabilistic it wouldn't even matter that much. Research seems to say the same thing I do, abeit with a lot more politicaly correct wrapping.

What effect size are you talking about? The heritability effect size? What is the "effect size" of a simple ratio of genetic variance to trait variance? What confounding effect do you think I'm suggesting to you?