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> Heritable != Molecular / Genetic Mechanism Hmm let me just check Wiktionary for "heritable" > Genetically transmissible from parent to offspring Ok then. M

> Heritable != Molecular / Genetic Mechanism Hmm let me just check Wiktionary for "heritable" > Genetically transmissible from parent to offspring Ok then. Maybe it has some specific meaning in biology? A search for "heritable meaning in biology" let me to this page: https://www.cancer.gov/publications/dictionaries/cancer-terms/def/heritable https://www.cancer.gov/publications/dictionaries/cancer-term... > In medicine, describes a characteristic or trait that can be passed from a parent to a child through the genes. IMO this post is dumb and the paper is perfectly clear to non-pedants.

IronyMan100 6mo ago
I heared the same distinction as OP, but it is the other way around, it's the degree to what a trait is inherited from you parents which cannot be explained by the enviroment or Random Chance.
tptacek 6mo ago
The heritability statistic that occurs in the literature is the ratio of genetic variance to phenotypic variance. Two corrollaries: * When discussing heritability results from the literature, we are discussing that statistic, not your intuitive understanding of what the word should mean. * In the scientific literature, your conception of heritability doesn't operate. In the scientific sense, the number of hands you have has low heritability, despite being genetically determined. I think you're going to find "let's check Wiktionary" is not the decisive move in these kinds of discussions that it is elsewhere.
- AgentME 6mo ago
  Another great example of the unintuitiveness of heritability is the fact that earrings are highly heritable. Earrings are highly correlated to a specific genetics (being female), so they're very "heritable", even though that correlation is an arbitrary cultural fashion.
  - lostmsu 6mo ago
    See my sibling comment. This is misleading for the same reason, but in this case the cause of misleading is narrowing the timespan under consideration to approximately now.
- lostmsu 6mo ago
  > In the scientific sense, the number of hands you have has low heritability, despite being genetically determined. This is only a surprise because unlike layman the author of this joke insists on considering heritability among humans specifically. While "heritability among humans" sounds like a reasonable comment to a layman, the author of this joke is misleading the layman, because layman (before being mislead) correctly thinks of "heritability" as "heritability among all living things with genes".
rbehrends 6mo ago
Heritability has a very specific meaning in quantitative genetics [1], which in many ways is not what your intuition would suggest [2]. It is this usage that the article talks about that. That said, there are plenty of critiques of this definition of heritability, and not just because it is different from what a layperson would expect it to mean. For example, the way it is used also usually has a big problem in that the standard formula assumes that Cov(G, E) = 0 (or at least is negligible), whereas in practice that is not actually true [3, 4]. This definition of heritability is also mathematically flawed in that it assumes (without evidence) that P = G + E, or at least can be reasonably approximated this way. Given that human development is the result of a feedback loop involving genetic and environmental factors, one would expect a model closer to something like a Markov chain. Proposed justifications of a simple additive model as an approximation (e.g. via the central limit theorem for highly polygenic traits) have to my knowledge never been tested. More recent genome-wide association studies [5] have actually shown a considerable gap between heritability estimates from genotype data and heritability estimates from twin studies, known as the "missing heritability problem". [1] https://en.wikipedia.org/wiki/Heritability https://en.wikipedia.org/wiki/Heritability [2] https://en.wikipedia.org/wiki/Genetic_variance https://en.wikipedia.org/wiki/Genetic_variance [3] https://en.wikipedia.org/wiki/Gene%E2%80%93environment_interaction https://en.wikipedia.org/wiki/Gene%E2%80%93environment_inter... [4] https://en.wikipedia.org/wiki/Gene%E2%80%93environment_correlation https://en.wikipedia.org/wiki/Gene%E2%80%93environment_corre... [5] https://en.wikipedia.org/wiki/Genome-wide_association_study https://en.wikipedia.org/wiki/Genome-wide_association_study
- IshKebab 6mo ago
  > Heritability has a very specific meaning in quantitative genetics [1] Literally the first paragraph of that page is > Heritability is a statistic used in the fields of breeding and genetics that estimates the degree of variation in a phenotypic trait in a population that is due to genetic variation between individuals in that population. 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?" That matches what I assumed it meant, and it seems like OP and the post are arguing that that is some kind of surprising interpretation. > OK, but check this out: Say I redefine “hair color” to mean “hair color except ignoring epigenetic and embryonic stuff and pretending that no one ever goes gray or dyes their hair et cetera”. Now, hair color is 100% heritable. Amazing, right? Uhm, no. That is exactly what I (and I think most people) would expect the answer to be.
hirvi74 6mo ago
There is a genetic component to alcohol use disorder, for example. But if one is in an environment where there is no access to alcohol whatsoever, then that person, despite their genes, will not develop an alcohol use disorder. The disorder can still be passed from parent to child, but it's more complicated than just genes.
kjs3 6mo ago
"Welcome to science hell, professor. This is IshKebab, he once saw something on the internet about your field of expertise and is going to spend eternity lecturing you on it."[1] [1] https://www.tomgauld.com/shop/science-hell-print https://www.tomgauld.com/shop/science-hell-print
imtringued 6mo ago
What you're expecting heritability to mean is essentially "are genes responsible for expressing this trait", which is very different from "can I get this trait from my parents?" which does not impose any particular method for passing on the trait. If the study doesn't use sequenced genes of parents and children as input into the model, it can't make the distinction between genetic or non genetic influence by parents.
- simiones 6mo ago
  That is exactly wrong. The measure of heritability used in the scientific literature is very much tied to genetics, just not in a very direct way. That is, heritability is a measure of how much of the variance in a trait is explained by genetics vs environment. In this sense, wealth will have a relatively low heritability, because it is weekly tied to genetics, even though it is very much a trait most people inherit from their parents. Skin color will have a high heritability, because the variance in skin color is almost entirely explained by genetics. The unintuitive part is that traits with almost no genetic variance at all, such as the number of arms, have very low heritability - since, in a population study, almost the entire variance in the number of arms will be explained by environmental factors (very very few families have 1 or 3 arms as a recurring trait - and there are way more people who lose their arms during life).

IronyMan100 6mo ago

I heared the same distinction as OP, but it is the other way around, it's the degree to what a trait is inherited from you parents which cannot be explained by the enviroment or Random Chance.

tptacek 6mo ago

The heritability statistic that occurs in the literature is the ratio of genetic variance to phenotypic variance. Two corrollaries: * When discussing heritability results from the literature, we are discussing that statistic, not your intuitive understanding of what the word should mean. * In the scientific literature, your conception of heritability doesn't operate. In the scientific sense, the number of hands you have has low heritability, despite being genetically determined. I think you're going to find "let's check Wiktionary" is not the decisive move in these kinds of discussions that it is elsewhere.

AgentME 6mo ago
Another great example of the unintuitiveness of heritability is the fact that earrings are highly heritable. Earrings are highly correlated to a specific genetics (being female), so they're very "heritable", even though that correlation is an arbitrary cultural fashion.
- lostmsu 6mo ago
  See my sibling comment. This is misleading for the same reason, but in this case the cause of misleading is narrowing the timespan under consideration to approximately now.
lostmsu 6mo ago
> In the scientific sense, the number of hands you have has low heritability, despite being genetically determined. This is only a surprise because unlike layman the author of this joke insists on considering heritability among humans specifically. While "heritability among humans" sounds like a reasonable comment to a layman, the author of this joke is misleading the layman, because layman (before being mislead) correctly thinks of "heritability" as "heritability among all living things with genes".

rbehrends 6mo ago

Heritability has a very specific meaning in quantitative genetics [1], which in many ways is not what your intuition would suggest [2]. It is this usage that the article talks about that. That said, there are plenty of critiques of this definition of heritability, and not just because it is different from what a layperson would expect it to mean. For example, the way it is used also usually has a big problem in that the standard formula assumes that Cov(G, E) = 0 (or at least is negligible), whereas in practice that is not actually true [3, 4]. This definition of heritability is also mathematically flawed in that it assumes (without evidence) that P = G + E, or at least can be reasonably approximated this way. Given that human development is the result of a feedback loop involving genetic and environmental factors, one would expect a model closer to something like a Markov chain. Proposed justifications of a simple additive model as an approximation (e.g. via the central limit theorem for highly polygenic traits) have to my knowledge never been tested. More recent genome-wide association studies [5] have actually shown a considerable gap between heritability estimates from genotype data and heritability estimates from twin studies, known as the "missing heritability problem". [1] https://en.wikipedia.org/wiki/Heritability https://en.wikipedia.org/wiki/Heritability [2] https://en.wikipedia.org/wiki/Genetic_variance https://en.wikipedia.org/wiki/Genetic_variance [3] https://en.wikipedia.org/wiki/Gene%E2%80%93environment_interaction https://en.wikipedia.org/wiki/Gene%E2%80%93environment_inter... [4] https://en.wikipedia.org/wiki/Gene%E2%80%93environment_correlation https://en.wikipedia.org/wiki/Gene%E2%80%93environment_corre... [5] https://en.wikipedia.org/wiki/Genome-wide_association_study https://en.wikipedia.org/wiki/Genome-wide_association_study

IshKebab 6mo ago
> Heritability has a very specific meaning in quantitative genetics [1] Literally the first paragraph of that page is > Heritability is a statistic used in the fields of breeding and genetics that estimates the degree of variation in a phenotypic trait in a population that is due to genetic variation between individuals in that population. 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?" That matches what I assumed it meant, and it seems like OP and the post are arguing that that is some kind of surprising interpretation. > OK, but check this out: Say I redefine “hair color” to mean “hair color except ignoring epigenetic and embryonic stuff and pretending that no one ever goes gray or dyes their hair et cetera”. Now, hair color is 100% heritable. Amazing, right? Uhm, no. That is exactly what I (and I think most people) would expect the answer to be.

hirvi74 6mo ago

There is a genetic component to alcohol use disorder, for example. But if one is in an environment where there is no access to alcohol whatsoever, then that person, despite their genes, will not develop an alcohol use disorder. The disorder can still be passed from parent to child, but it's more complicated than just genes.

kjs3 6mo ago

"Welcome to science hell, professor. This is IshKebab, he once saw something on the internet about your field of expertise and is going to spend eternity lecturing you on it."[1] [1] https://www.tomgauld.com/shop/science-hell-print https://www.tomgauld.com/shop/science-hell-print

imtringued 6mo ago

What you're expecting heritability to mean is essentially "are genes responsible for expressing this trait", which is very different from "can I get this trait from my parents?" which does not impose any particular method for passing on the trait. If the study doesn't use sequenced genes of parents and children as input into the model, it can't make the distinction between genetic or non genetic influence by parents.

simiones 6mo ago
That is exactly wrong. The measure of heritability used in the scientific literature is very much tied to genetics, just not in a very direct way. That is, heritability is a measure of how much of the variance in a trait is explained by genetics vs environment. In this sense, wealth will have a relatively low heritability, because it is weekly tied to genetics, even though it is very much a trait most people inherit from their parents. Skin color will have a high heritability, because the variance in skin color is almost entirely explained by genetics. The unintuitive part is that traits with almost no genetic variance at all, such as the number of arms, have very low heritability - since, in a population study, almost the entire variance in the number of arms will be explained by environmental factors (very very few families have 1 or 3 arms as a recurring trait - and there are way more people who lose their arms during life).