7 ms·

But heritability is a statistic that is specifically designed to distinguish between genetic and environmental factors. A trait whose variance has no genetic i

But heritability is a statistic that is specifically designed to distinguish between genetic and environmental factors. A trait whose variance has no genetic influence would have 0 heritability, unless I am missing something.

tptacek 4y ago
Heritability is the ratio of genetically-produced variation to total variation in some population. Overwhelmingly people who wear lipstick have a clear genetic difference from those who don't (XX vs. XY). It's a degenerate example meant to illustrate the point: heritability doesn't answer the question of genetic influence, but rather reframes it.
- haberman 4y ago
  Ok I think I am with you now. You are saying that lipstick-wearing variation is very strongly influenced by genes (namely XX vs. XY chromosomes), and is thus highly heritable by the definition of heritability, but is somewhat paradoxical in that XX genes do not directly cause a person to put on lipstick in the same way that, say, XX genes make a person capable of bearing a child.
  - sfblah 4y ago
    This heritability redefinition thing is just a bad-faith move by people on the left to avoid the debate in my opinion. The standard historical understanding of the word "heritability" is exactly what you said. It's like redefining gender or sex or the like.
    - tptacek 4y ago
      You're just waiting for someone to attempt this argument, and now you have, and so I get to make the simple observation: the research results establishing heritability use the actual scientific definition of heritability, not whatever definition is most intuitive to you. When you reference those results while redefining terms they're using, you invent new, bogus results out of whole cloth. That this happened here is evident from the fact that you've been reduced to arguments like "IQ is genetically determined because my cat can't play chess".
      - sfblah 4y ago
        No. This definition of heritability is an obvious wokeism. https://www.etymonline.com/word/heritable#:~:text=%22capable%20of%20being%20inherited%2C%20inheritable,Related%3A%20Heritability https://www.etymonline.com/word/heritable#:~:text=%22capable.... https://dictionary.cambridge.org/dictionary/english/heritability https://dictionary.cambridge.org/dictionary/english/heritabi... The Cambridge definition linked just above is particularly on point: "The ability of a disease or characteristic to be passed from a parent or grandparent to a child through the genes" -- Yes, I know it's convenient to redefine terms like gender and heritability to fit what's politically popular. I get it. But, don't gaslight me by telling me I'm redefining the words. As you can see, I could have used this word in 1300s France and been understood as speaking about traits derived from one's parents through being their offspring. -- As for my argument about a cat playing chess, I'm just trying to give you the simplest possible example so you can see that your doctrinaire position on this subject is insane.
        tptacek 4y ago
        The definition I've offered you is the same one Richard Lynn uses.
        sfblah 4y ago
        Before this thread I didn't even know who Richard Lynn was. Now I do, but I don't care. Look, I gave you the etymology of the word and the current definition. Both disagree with your wokeism. This is getting tiresome.
        tptacek 4y ago
        In case the subtext wasn't clear, the definition I'm providing for "heritability" is the scientific definition, and has been for decades. My understanding is that it comes from woke biostatisticians like Karl Pearson, who applied it to the woke problem of working out how to select and propagate characteristics in agricultural products, back in the woke 1930s. Somebody can correct me on this if I have the chronology wrong. I'm happy to keep going on like this, because you're surfacing a lot of pernicious "race science" myths in their absolute most easily rebutted form, which is (and here truly there is no snark intended) a sort of service to the thread.
  - tptacek 4y ago
    Exactly. Similarly, your number of toes is directly determined by genes, but it has relatively low heritability, because heritability is a measure of variability, and most toe count variations are environmental (thalidomide is the classic example).
    - Natsu 4y ago
      I was curious about the argument you seem to be making here, so I ran it past a researcher I am acquainted with and he said this (with some minor edits for clarity): In the case of IQ, we can identify the model through the exogenous quantity "relatedness." We know exactly how related monozygotic twins are (100%) and the expectation for dizygotic twin relatedness (50%), so we can use the fact that these quantities are known to figure out other model parameters. Since we know that dizygotic twins are exactly half as related as monozygotic ones in the limit, we know the the genetic effect is going to be equal to 2(r_{MZ} - r_{DZ}) and excess resemblance cannot be attributable to genes, since dizygotic twins are not >50% related (on average). Therefore, we can use it to directly figure out the fraction attributable to genetics, then we can see the excess relatedness as due to shared environments, and the residual as the unshared.
      - tptacek 4y ago
        This gets us into stuff like the ACE model, and I'm not arguing about cog psych research practices, I'm only here for the concept of heritability, which is misrepresented on threads like these. This is a pretty good high-level summary: https://fnew.github.io/posts/2019/11/blog_post_ACE_model/ https://fnew.github.io/posts/2019/11/blog_post_ACE_model/
        deleted 4y ago
        [deleted]
  - astrange 4y ago
    Remember, correlation is not causation. Causation can be determined by experiments (either "natural experiments" or intervention studies), but obviously these are both technically impossible and usually immoral to do on humans. Some fields like (…parts of) economics and medicine do experiment design properly, but many others (genetics, psychology, nutrition) just kind of ignore it and hand-wave something about P-values. This is ok if you're only using genetics to create 23AndMe ancestry charts, but it won't be once we actually have gene editing capabilities to inform.
    - sfblah 4y ago
      [flagged]
runarberg 4y ago
> Suppose you buy a bag of seed corn from a hardware store. This is not some sort of fancy cloned corn, but ordinary genetically varied corn of the sort that farmers planted long before there was a science of genetics. Grow one handful of it in a carefully controlled environment in which the seeds get uniform illumination and uniform nutrient solution. The corn plants will vary in height, and because the environment is uniform, the heritability of height will be 100 percent. Now take another handful of corn from the same bag, and grow it in a similarly uniform environment but with a uniformly poor nutrient solution. Again, the plants will vary in height, but all will be stunted. Once more the heritability of height is 100 percent. Despite the 100 percent heritabilities of height within each group, the difference in height between the groups is entirely environmentally caused. So we can have total heritability within groups, substantial variation between groups, but no genetic difference between the groups. https://web-archive.southampton.ac.uk/cogprints.org/230/1/199712003.html https://web-archive.southampton.ac.uk/cogprints.org/230/1/19...

tptacek 4y ago

Heritability is the ratio of genetically-produced variation to total variation in some population. Overwhelmingly people who wear lipstick have a clear genetic difference from those who don't (XX vs. XY). It's a degenerate example meant to illustrate the point: heritability doesn't answer the question of genetic influence, but rather reframes it.

haberman 4y ago
Ok I think I am with you now. You are saying that lipstick-wearing variation is very strongly influenced by genes (namely XX vs. XY chromosomes), and is thus highly heritable by the definition of heritability, but is somewhat paradoxical in that XX genes do not directly cause a person to put on lipstick in the same way that, say, XX genes make a person capable of bearing a child.
- sfblah 4y ago
  This heritability redefinition thing is just a bad-faith move by people on the left to avoid the debate in my opinion. The standard historical understanding of the word "heritability" is exactly what you said. It's like redefining gender or sex or the like.
  - tptacek 4y ago
    You're just waiting for someone to attempt this argument, and now you have, and so I get to make the simple observation: the research results establishing heritability use the actual scientific definition of heritability, not whatever definition is most intuitive to you. When you reference those results while redefining terms they're using, you invent new, bogus results out of whole cloth. That this happened here is evident from the fact that you've been reduced to arguments like "IQ is genetically determined because my cat can't play chess".
    - sfblah 4y ago
      No. This definition of heritability is an obvious wokeism. https://www.etymonline.com/word/heritable#:~:text=%22capable%20of%20being%20inherited%2C%20inheritable,Related%3A%20Heritability https://www.etymonline.com/word/heritable#:~:text=%22capable.... https://dictionary.cambridge.org/dictionary/english/heritability https://dictionary.cambridge.org/dictionary/english/heritabi... The Cambridge definition linked just above is particularly on point: "The ability of a disease or characteristic to be passed from a parent or grandparent to a child through the genes" -- Yes, I know it's convenient to redefine terms like gender and heritability to fit what's politically popular. I get it. But, don't gaslight me by telling me I'm redefining the words. As you can see, I could have used this word in 1300s France and been understood as speaking about traits derived from one's parents through being their offspring. -- As for my argument about a cat playing chess, I'm just trying to give you the simplest possible example so you can see that your doctrinaire position on this subject is insane.
      - tptacek 4y ago
        The definition I've offered you is the same one Richard Lynn uses.
        sfblah 4y ago
        Before this thread I didn't even know who Richard Lynn was. Now I do, but I don't care. Look, I gave you the etymology of the word and the current definition. Both disagree with your wokeism. This is getting tiresome.
        tptacek 4y ago
        In case the subtext wasn't clear, the definition I'm providing for "heritability" is the scientific definition, and has been for decades. My understanding is that it comes from woke biostatisticians like Karl Pearson, who applied it to the woke problem of working out how to select and propagate characteristics in agricultural products, back in the woke 1930s. Somebody can correct me on this if I have the chronology wrong. I'm happy to keep going on like this, because you're surfacing a lot of pernicious "race science" myths in their absolute most easily rebutted form, which is (and here truly there is no snark intended) a sort of service to the thread.
- tptacek 4y ago
  Exactly. Similarly, your number of toes is directly determined by genes, but it has relatively low heritability, because heritability is a measure of variability, and most toe count variations are environmental (thalidomide is the classic example).
  - Natsu 4y ago
    I was curious about the argument you seem to be making here, so I ran it past a researcher I am acquainted with and he said this (with some minor edits for clarity): In the case of IQ, we can identify the model through the exogenous quantity "relatedness." We know exactly how related monozygotic twins are (100%) and the expectation for dizygotic twin relatedness (50%), so we can use the fact that these quantities are known to figure out other model parameters. Since we know that dizygotic twins are exactly half as related as monozygotic ones in the limit, we know the the genetic effect is going to be equal to 2(r_{MZ} - r_{DZ}) and excess resemblance cannot be attributable to genes, since dizygotic twins are not >50% related (on average). Therefore, we can use it to directly figure out the fraction attributable to genetics, then we can see the excess relatedness as due to shared environments, and the residual as the unshared.
    - tptacek 4y ago
      This gets us into stuff like the ACE model, and I'm not arguing about cog psych research practices, I'm only here for the concept of heritability, which is misrepresented on threads like these. This is a pretty good high-level summary: https://fnew.github.io/posts/2019/11/blog_post_ACE_model/ https://fnew.github.io/posts/2019/11/blog_post_ACE_model/
      - deleted 4y ago
        [deleted]
- astrange 4y ago
  Remember, correlation is not causation. Causation can be determined by experiments (either "natural experiments" or intervention studies), but obviously these are both technically impossible and usually immoral to do on humans. Some fields like (…parts of) economics and medicine do experiment design properly, but many others (genetics, psychology, nutrition) just kind of ignore it and hand-wave something about P-values. This is ok if you're only using genetics to create 23AndMe ancestry charts, but it won't be once we actually have gene editing capabilities to inform.
  - sfblah 4y ago
    [flagged]

runarberg 4y ago

> Suppose you buy a bag of seed corn from a hardware store. This is not some sort of fancy cloned corn, but ordinary genetically varied corn of the sort that farmers planted long before there was a science of genetics. Grow one handful of it in a carefully controlled environment in which the seeds get uniform illumination and uniform nutrient solution. The corn plants will vary in height, and because the environment is uniform, the heritability of height will be 100 percent. Now take another handful of corn from the same bag, and grow it in a similarly uniform environment but with a uniformly poor nutrient solution. Again, the plants will vary in height, but all will be stunted. Once more the heritability of height is 100 percent. Despite the 100 percent heritabilities of height within each group, the difference in height between the groups is entirely environmentally caused. So we can have total heritability within groups, substantial variation between groups, but no genetic difference between the groups. https://web-archive.southampton.ac.uk/cogprints.org/230/1/199712003.html https://web-archive.southampton.ac.uk/cogprints.org/230/1/19...