4 ms·

people really don't want to accept that beyond the most extreme cases(starvation, lead poisoning, complete neglect, no school access at all, etc.), environment

people really don't want to accept that beyond the most extreme cases(starvation, lead poisoning, complete neglect, no school access at all, etc.), environment really doesn't play that big of a role. Twin studies have shown this for literally decades

astrange 2y ago
Lead poisoning isn't an extreme case, it's a very common problem. Twin studies don't exclude environmental causes because twins have the same maternal environment.
- drowsspa 2y ago
  Yeah, I never got how the womb doesn't count as an environment, and even the circumstances that led to the twins being separated.
  - somenameforme 2y ago
    While commonly thought, this isn't how twin usually studies work. The way it works is you look at the correlation between identical and non-identical twins on some given thing. If there's a much stronger correlation between the identical twins, then it's probably primarily genetic. What this does is helps to eliminate environmental factors because identical vs nonidentical twins will both be raised in basically the exact same environment. So take height. If identical twins have identical heights while non-identical twins have varying heights, then it's safe to assume height is largely genetic. Interestingly separated twins would actually be worse in many cases because you reintroduce environmental deviation. For instance with height, differences may well be down to e.g. nutrition, but when you have them in the same household you can usually assume roughly identical nutrition.
lovethevoid 2y ago
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.
travisjungroth 2y ago
That’s not what the twin studies have shown. It’s not only the most extreme cases, it’s anything short of the very good circumstances. For example, the stable homes families have to prove they have to adopt. Cyril-f “twin”. https://www.robkhenderson.com/p/no-one-expects-young-men-to-do-anything https://www.robkhenderson.com/p/no-one-expects-young-men-to-...

astrange 2y ago

Lead poisoning isn't an extreme case, it's a very common problem. Twin studies don't exclude environmental causes because twins have the same maternal environment.

drowsspa 2y ago
Yeah, I never got how the womb doesn't count as an environment, and even the circumstances that led to the twins being separated.
- somenameforme 2y ago
  While commonly thought, this isn't how twin usually studies work. The way it works is you look at the correlation between identical and non-identical twins on some given thing. If there's a much stronger correlation between the identical twins, then it's probably primarily genetic. What this does is helps to eliminate environmental factors because identical vs nonidentical twins will both be raised in basically the exact same environment. So take height. If identical twins have identical heights while non-identical twins have varying heights, then it's safe to assume height is largely genetic. Interestingly separated twins would actually be worse in many cases because you reintroduce environmental deviation. For instance with height, differences may well be down to e.g. nutrition, but when you have them in the same household you can usually assume roughly identical nutrition.

lovethevoid 2y ago

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.

travisjungroth 2y ago

That’s not what the twin studies have shown. It’s not only the most extreme cases, it’s anything short of the very good circumstances. For example, the stable homes families have to prove they have to adopt. Cyril-f “twin”. https://www.robkhenderson.com/p/no-one-expects-young-men-to-do-anything https://www.robkhenderson.com/p/no-one-expects-young-men-to-...