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That's not true, for example metacognitive ability studies have shown environment plays the dominant role. Twin studies on trust provide the same, in which gene

That's not true, for example metacognitive ability studies have shown environment plays the dominant role. Twin studies on trust provide the same, in which genetic component while large at 33% certainly doesn't indicate what you're stating that it's only "extreme cases". Even in studies re-assessing conventional twin studies and educational attainment, the conclusion was that while some is genetic (sometimes even a large portion) the correlations between a mother and father's educational attainment points to environment playing a large role (unless you have the belief that the mother and father are siblings I suppose). You'll be extremely hard pressed to find researchers conducting these twin studies who minimize the role of either genetic or environmental impact on certain aspects in the way you did.

somenameforme 2y ago
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

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.