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There's a tricky (and super interesting) thing with IQ studies. Environmental factors play a dominant role early on, but genetics becomes more and more dominant

There's a tricky (and super interesting) thing with IQ studies. Environmental factors play a dominant role early on, but genetics becomes more and more dominant as a person ages; significant privilege or disadvantage earlier in life notwithstanding (excepting major physical impairment by nutrition, lead, etc)! Most studies tend to find the heritability of adult IQ at around 80%. Any research on this area is walking on egg shells and so researchers are highly incentivized to overemphasize possible environmental explanations. Nature formalized this threat/risk with their relatively recent announcement [1], but it seems to have been an unspoken 'rule' for decades at least. [1] - https://www.nature.com/articles/s41562-022-01443-2 https://www.nature.com/articles/s41562-022-01443-2

tptacek 2y ago
Heritability is not genetic determination; your environment is inherited as well. The Nature link you've provided doesn't address anything you wrote in your comment.
- somenameforme 2y ago
  Heritability is, literally by definition, the measured difference in some value (like IQ) between people that is attributable to genetics alone. There's quite a lot of clever ways to control for environmental factors, like twin studies. And I simply think you're not engaging in good faith whatsoever if you don't see how that Nature article creates a huge chilling effect on any discussion of genetics.
  - tptacek 2y ago
    Heritability is the ratio of genetic variation to total variation. Lipstick-wearing is highly heritable; the number of hands and feet you have is not. As I said, and as you can see, the heritability of a trait tells you nothing at all about its genetic determination. I don't know what to tell you about the cite you gave, since it simply doesn't say what you said it says.
    - somenameforme 2y ago
      You sound like you're thinking of things colloquially, to put things in a kind way. Heritability is not a colloquial term and in biology/genetics refers exclusively to genetic factors. In particular it's the percent of difference in some value that cannot be explained by non-genetic factors. So e.g. if my IQ is 130 and yours is 90 then we'd have a difference of 40 points. With an adult IQ heritability of 80% we'd expect that about 32 points of that would be unable to explained outside of genetic factors. Heritability does change over time because environments change over time. For instance in an area where starvation, lead poisoning, and malnutrition was common, the heritability of intelligence (or height) would generally be quite low, because the aforementioned environmental factors would be able to explain a large chunk of the differences between populations. But in a society where everybody had practically identical relevant upbringings and opportunities, the heritability of intelligence would be 100%, because the only difference between people would be genetic. One of the many ways to test for heritability is twin studies. You'll likely find the correlation between lipstick wearing between identical and non-identical twins would be near to 100%. This means that the heritability of the trait would be near 0%.
      - tptacek 2y ago
        No, I just provided you the literal technical definition of "heritability". It should be immediately apparent to you why lipstick is (highly) heritable and hand count isn't†; if it isn't, you're the one working from the "colloquial" understanding. † lipstick: highly dependent on XX vs. XY; hands: set by highly conserved Hox genes, variation virtually entirely due to environmental factors.
        somenameforme 2y ago
        I'm going to assume you're not trolling, and I am also going to assume you're the type of person that would take Wiki as a reliable source, so here you go: --- "The concept of heritability can be expressed in the form of the following question: "What is the proportion of the variation in a given trait within a population that is not explained by the environment or random chance?"[2]" --- The within a population part is critical. I'd encourage looking up twin studies to understand one way this percentage is estimated. I assume you think you know how they are done - you do not, because it directly leads into an understanding of how things like lipstick wearing would be near 0% heritable, while things like handcount at birth would be near 100% heritable. [1] - https://en.wikipedia.org/wiki/Heritability https://en.wikipedia.org/wiki/Heritability

tptacek 2y ago

Heritability is not genetic determination; your environment is inherited as well. The Nature link you've provided doesn't address anything you wrote in your comment.

somenameforme 2y ago
Heritability is, literally by definition, the measured difference in some value (like IQ) between people that is attributable to genetics alone. There's quite a lot of clever ways to control for environmental factors, like twin studies. And I simply think you're not engaging in good faith whatsoever if you don't see how that Nature article creates a huge chilling effect on any discussion of genetics.
- tptacek 2y ago
  Heritability is the ratio of genetic variation to total variation. Lipstick-wearing is highly heritable; the number of hands and feet you have is not. As I said, and as you can see, the heritability of a trait tells you nothing at all about its genetic determination. I don't know what to tell you about the cite you gave, since it simply doesn't say what you said it says.
  - somenameforme 2y ago
    You sound like you're thinking of things colloquially, to put things in a kind way. Heritability is not a colloquial term and in biology/genetics refers exclusively to genetic factors. In particular it's the percent of difference in some value that cannot be explained by non-genetic factors. So e.g. if my IQ is 130 and yours is 90 then we'd have a difference of 40 points. With an adult IQ heritability of 80% we'd expect that about 32 points of that would be unable to explained outside of genetic factors. Heritability does change over time because environments change over time. For instance in an area where starvation, lead poisoning, and malnutrition was common, the heritability of intelligence (or height) would generally be quite low, because the aforementioned environmental factors would be able to explain a large chunk of the differences between populations. But in a society where everybody had practically identical relevant upbringings and opportunities, the heritability of intelligence would be 100%, because the only difference between people would be genetic. One of the many ways to test for heritability is twin studies. You'll likely find the correlation between lipstick wearing between identical and non-identical twins would be near to 100%. This means that the heritability of the trait would be near 0%.
    - tptacek 2y ago
      No, I just provided you the literal technical definition of "heritability". It should be immediately apparent to you why lipstick is (highly) heritable and hand count isn't†; if it isn't, you're the one working from the "colloquial" understanding. † lipstick: highly dependent on XX vs. XY; hands: set by highly conserved Hox genes, variation virtually entirely due to environmental factors.
      - somenameforme 2y ago
        I'm going to assume you're not trolling, and I am also going to assume you're the type of person that would take Wiki as a reliable source, so here you go: --- "The concept of heritability can be expressed in the form of the following question: "What is the proportion of the variation in a given trait within a population that is not explained by the environment or random chance?"[2]" --- The within a population part is critical. I'd encourage looking up twin studies to understand one way this percentage is estimated. I assume you think you know how they are done - you do not, because it directly leads into an understanding of how things like lipstick wearing would be near 0% heritable, while things like handcount at birth would be near 100% heritable. [1] - https://en.wikipedia.org/wiki/Heritability https://en.wikipedia.org/wiki/Heritability