4 ms·

An interesting tidbit in the nature vs. nurture debate is that nature and nurture interplay in ways you might not expect. For instance, height is approximately

An interesting tidbit in the nature vs. nurture debate is that nature and nurture interplay in ways you might not expect. For instance, height is approximately 90% heritable in the United States -- but this does not mean that in a vacuum height is mostly genetic. It means that in the United States nutrition has mostly been solved (and yes, even the "food insecure" in the US rarely lack for the actual calories which would impact their height -- food insecurity causes other problems) and therefore the only real differences that can remain are the genetic differences. It might be useful to look at any twin study through this lens; if we know for sure the genes are the same and nature is off the table, how much variance remains?

tptacek 11mo ago
In all these discussions it's helpful to understand the definition of broad-sense heritability (the statistic almost always in play when we're discussing heritability) --- it's a correlation, not a demonstrated causation, and your environment (and gene/environment interactions) are inherited as well.
the__alchemist 11mo ago
Things get even fuzzier when you throw in heritable epigenetics too. We have a balance of these factors at least: - Genetics (DNA seq) - Epigentics (Histone acetylation, base methylation etc) - Brain wiring from experiences - Chemical impact from experiences, e.g. nutrition, toxins, sunlight, muscle dev etc etc.
- everdrive 11mo ago
  > - Brain wiring from experiences > - Chemical impact from experiences, e.g. nutrition, toxins, sunlight, muscle dev etc etc. Are these not all part of the nurture / environment bucket? Or are we drawing a hard boundary between nurture (eg, parenting) and environment? (eg, lead in the pipes)
  - the__alchemist 11mo ago
    I'm splitting up both "nature" and "nurture" into slightly less-broad categories. In the case of what you highlighted, yes. For example, epigentics is sort of both "nature" and "nurture", in that you can pick up these traits, and pass them on/get them passed on.
    - sudosysgen 11mo ago
      They can also simply get picked up in a correlated manner between twins due to the shared womb environment even if those correlated epigenetic traits are completely different from those of the parents.
  - tptacek 11mo ago
    Genes interact with the environment. There aren't hard boundaries the way you've phrased them.
- Aurornis 11mo ago
  > Things get even fuzzier when you throw in heritable epigenetics too. Heritable epigenetics is a nascent field. We have yet to get any real promising research showing it even occurs to a significant degree in human. I would assume it's not a significant factor until we can find even some minimal evidence to suggest that it's an influence in humans. Even then, my guess is that the impact would be minimal. I know this is contrary to a lot of the "trauma passed down through epigenetics" narratives that are going around, but the actual science is in a very different place than the popular understanding of the topic.
  - tptacek 11mo ago
    Whether or not epigenetic effects are passed down, epigenetics almost certainly impacts trait expression and complicates the "innate vs. environmental" narrative of hereditarians. I don't believe "inherited trauma" woo either, but epigenetics is much more fundamental to genetic science than that.
    - Aurornis 11mo ago
      Traditional epigenetics is very different than heritable epigenetics. Epigenetics is most definitely a factor in humans. Heritable epigenetics is a different story. There is some early evidence suggesting that transgenerational epigenetic effects appear in humans, but it's very early. Some of the first claimed discoveries of transgenerational epigenetic inheritance in humans turned out to be mistakes by researchers. A lot of the theories about human transgenerational epigenetic inheritance revolve around exposure to famines and food crises, which is unfortunately complicated by the way food crises shape dietary behaviors and eating habits which are also passed down via tradition (not genetically). The difficult part is that journalists often use "epigenetics" to refer to heritable epigenetics, and a lot of commenters make the same mistake.
      - tptacek 11mo ago
        Right, I'm not pushing back on you, just sticking up for the idea of paying attention to epigenetic factors in this broader question of innateness.
churchill 11mo ago
[dead]
gishh 11mo ago
As an anecdote: late 30s male, mother was 5'6 father was 5'9, I'm 6'4. I have three kids with two different women. All 3 are blonde-haired/blue-eyed. I have brown hair and green eyes, my ex has brown hair and blue eyes, and my spouse has blonde hair and blue eyes. Not as interesting I suppose. Yes, they're all my kids biologically. :)
xattt 11mo ago
Re: nutrition I am curious about the influence on height by self-limited diets in children who are picky eaters. Is there some self-regulation process that decreases pickiness when nutritional status is at risk?
- terminalshort 11mo ago
  Is anybody actually picky enough to create a calorie or nutrient deficiency? I would think evolution would have harshly selected against such a behavior.
  - addaon 11mo ago
    Yes. See e.g. anorexia nervosa.
SilverElfin 11mo ago
That’s a good way to put it - eliminating other factors ends up deceptively making it look like genetics are the only difference. On the topic of IQ, the importance of those other factors is implied by things like the Flynn effect (https://en.wikipedia.org/wiki/Flynn_effect#Proposed_explanations https://en.wikipedia.org/wiki/Flynn_effect#Proposed_explanat...)? It’s also evident in how IQ varies by country. In developing countries, average IQ can measure low due to issues like malnutrition, access to education, etc. Those differences change as those countries develop or across different parts of those countries or when you track immigration populations from those countries. Oddly, denial of these other variables has become core to scientific racism (https://en.wikipedia.org/wiki/Scientific_racism https://en.wikipedia.org/wiki/Scientific_racism). For example, a Danish white supremacist named Emil Kirkegaard went so far as to create a fake journal (https://en.wikipedia.org/wiki/OpenPsych https://en.wikipedia.org/wiki/OpenPsych) to publish flagrantly incorrect papers on IQ that try to deny these factors and paint the IQ of non-white countries as low, with the only explanation being their “inferior” race/genetics. In fact, he just recently wrote a new “paper” (https://openpsych.net/paper/85/ https://openpsych.net/paper/85/) that has been widely retweeted by supremacists on X.
- lo_zamoyski 11mo ago
  > denial of these other variables has become core to scientific racism Scientific racism has always operated this way. When it wasn't fabricating evidence, it was cherry-picking or failing to account for environmental causes. It would be interesting to see how historical claims made in this context hold up (I would expect to see changes that negate the claims; something that comes to mind is that the Dutch were one of the shortest peoples in Europe, but later in the 19th century became one of the tallest). > flagrantly incorrect papers on IQ that try to deny these factors and paint the IQ of non-white countries as low, with the only explanation being their “inferior” race/genetics I think the more important point we need to remember is that even if we were to discover that some groups have a genetic predisposition for higher IQ (putting aside the controversial nature of IQ to begin with), those with predisposition for lower IQ are still human and thus still owed what is due by virtue of their basic human dignity. It's also possible that over time, adaptation would change this predisposition. Populations aren't static.
skybrian 11mo ago
I don't fully understand this blog post, but possibly of interest: https://theinfinitesimal.substack.com/p/the-missing-heritability-question https://theinfinitesimal.substack.com/p/the-missing-heritabi... In particular, see the third chart, "GREML-WGS heritability estimates," which shows that heritability for height is pretty much the same when they try to adjust for environment in different ways, while the estimates for IQ vary a lot. Gusev seems convinced that some environmental effect is inflating heritability estimates for IQ that are based on twin studies.
delichon 11mo ago
> It means that in the United States nutrition has mostly been solved Nature is not off of the table. We've just traded problems with calorie quantity to quality. condition US prevalence hypertension 49% obesity 40% metabolic syndrome 40% prediabetes 38% fatty liver disease 25% diabetes 16% coronary disease 5% That's not mostly solved, that's tens of millions of truncated, immiserated lives. Of course calorie quality differences are important to child development.
- tptacek 11mo ago
  I think you'll find in comparisons of 2025 to the turn of the 20th century that we lives are, by comparison, neither truncated nor immiserated. Anyways, this has nothing to do with the topic of the thread.
  - delichon 11mo ago
    My argument is that we cannot simply say, they're both getting enough calories, therefore we can discount the nutritional component of their IQ differences. Sufficient calories do not remove nutrition as a confound.
    - tptacek 11mo ago
      You're handwaving away the nutrition hypothesis for the Flynn Effect, and I think losing sight of the timeline for the comparison. It's going to be very difficult to make any case like this if we're looking back to 1900, which is what we're doing when we talk about the nutrition/intelligence shifts we see in stats.
      - delichon 11mo ago
        We seem to be having different conversations. I'm responding to if we know for sure the genes are the same and nature is off the table, how much variance remains? ... and saying that nature isn't off the table at all. Are you saying that it is?
underlipton 11mo ago
>and therefore the only real differences that can remain are the genetic differences. Incidence of undiagnosed digestive and sleep disorders, like celiac disease and sleep apnea, respectively. "Catch-up" growth occurs almost universally after treatment starts, which means that the growth trajectory was lower than the "genetic potential", and likely remains so for children who can't access treatment. Multiply across any number of silent or untreated disorders, sensitivities, or insufficiencies. Adult height also isn't 90% heritable in the US. It only reaches that high a percentage of heritability in studies involving closely-related populations. In which case, of course; in populations with low genetic and cultural diversity and moderate or high variability, small differences are magnified.

tptacek 11mo ago

In all these discussions it's helpful to understand the definition of broad-sense heritability (the statistic almost always in play when we're discussing heritability) --- it's a correlation, not a demonstrated causation, and your environment (and gene/environment interactions) are inherited as well.

the__alchemist 11mo ago

Things get even fuzzier when you throw in heritable epigenetics too. We have a balance of these factors at least: - Genetics (DNA seq) - Epigentics (Histone acetylation, base methylation etc) - Brain wiring from experiences - Chemical impact from experiences, e.g. nutrition, toxins, sunlight, muscle dev etc etc.

everdrive 11mo ago
> - Brain wiring from experiences > - Chemical impact from experiences, e.g. nutrition, toxins, sunlight, muscle dev etc etc. Are these not all part of the nurture / environment bucket? Or are we drawing a hard boundary between nurture (eg, parenting) and environment? (eg, lead in the pipes)
- the__alchemist 11mo ago
  I'm splitting up both "nature" and "nurture" into slightly less-broad categories. In the case of what you highlighted, yes. For example, epigentics is sort of both "nature" and "nurture", in that you can pick up these traits, and pass them on/get them passed on.
  - sudosysgen 11mo ago
    They can also simply get picked up in a correlated manner between twins due to the shared womb environment even if those correlated epigenetic traits are completely different from those of the parents.
- tptacek 11mo ago
  Genes interact with the environment. There aren't hard boundaries the way you've phrased them.
Aurornis 11mo ago
> Things get even fuzzier when you throw in heritable epigenetics too. Heritable epigenetics is a nascent field. We have yet to get any real promising research showing it even occurs to a significant degree in human. I would assume it's not a significant factor until we can find even some minimal evidence to suggest that it's an influence in humans. Even then, my guess is that the impact would be minimal. I know this is contrary to a lot of the "trauma passed down through epigenetics" narratives that are going around, but the actual science is in a very different place than the popular understanding of the topic.
- tptacek 11mo ago
  Whether or not epigenetic effects are passed down, epigenetics almost certainly impacts trait expression and complicates the "innate vs. environmental" narrative of hereditarians. I don't believe "inherited trauma" woo either, but epigenetics is much more fundamental to genetic science than that.
  - Aurornis 11mo ago
    Traditional epigenetics is very different than heritable epigenetics. Epigenetics is most definitely a factor in humans. Heritable epigenetics is a different story. There is some early evidence suggesting that transgenerational epigenetic effects appear in humans, but it's very early. Some of the first claimed discoveries of transgenerational epigenetic inheritance in humans turned out to be mistakes by researchers. A lot of the theories about human transgenerational epigenetic inheritance revolve around exposure to famines and food crises, which is unfortunately complicated by the way food crises shape dietary behaviors and eating habits which are also passed down via tradition (not genetically). The difficult part is that journalists often use "epigenetics" to refer to heritable epigenetics, and a lot of commenters make the same mistake.
    - tptacek 11mo ago
      Right, I'm not pushing back on you, just sticking up for the idea of paying attention to epigenetic factors in this broader question of innateness.

churchill 11mo ago

[dead]

gishh 11mo ago

As an anecdote: late 30s male, mother was 5'6 father was 5'9, I'm 6'4. I have three kids with two different women. All 3 are blonde-haired/blue-eyed. I have brown hair and green eyes, my ex has brown hair and blue eyes, and my spouse has blonde hair and blue eyes. Not as interesting I suppose. Yes, they're all my kids biologically. :)

xattt 11mo ago

Re: nutrition I am curious about the influence on height by self-limited diets in children who are picky eaters. Is there some self-regulation process that decreases pickiness when nutritional status is at risk?

terminalshort 11mo ago
Is anybody actually picky enough to create a calorie or nutrient deficiency? I would think evolution would have harshly selected against such a behavior.
- addaon 11mo ago
  Yes. See e.g. anorexia nervosa.

SilverElfin 11mo ago

That’s a good way to put it - eliminating other factors ends up deceptively making it look like genetics are the only difference. On the topic of IQ, the importance of those other factors is implied by things like the Flynn effect (https://en.wikipedia.org/wiki/Flynn_effect#Proposed_explanations https://en.wikipedia.org/wiki/Flynn_effect#Proposed_explanat...)? It’s also evident in how IQ varies by country. In developing countries, average IQ can measure low due to issues like malnutrition, access to education, etc. Those differences change as those countries develop or across different parts of those countries or when you track immigration populations from those countries. Oddly, denial of these other variables has become core to scientific racism (https://en.wikipedia.org/wiki/Scientific_racism https://en.wikipedia.org/wiki/Scientific_racism). For example, a Danish white supremacist named Emil Kirkegaard went so far as to create a fake journal (https://en.wikipedia.org/wiki/OpenPsych https://en.wikipedia.org/wiki/OpenPsych) to publish flagrantly incorrect papers on IQ that try to deny these factors and paint the IQ of non-white countries as low, with the only explanation being their “inferior” race/genetics. In fact, he just recently wrote a new “paper” (https://openpsych.net/paper/85/ https://openpsych.net/paper/85/) that has been widely retweeted by supremacists on X.

lo_zamoyski 11mo ago
> denial of these other variables has become core to scientific racism Scientific racism has always operated this way. When it wasn't fabricating evidence, it was cherry-picking or failing to account for environmental causes. It would be interesting to see how historical claims made in this context hold up (I would expect to see changes that negate the claims; something that comes to mind is that the Dutch were one of the shortest peoples in Europe, but later in the 19th century became one of the tallest). > flagrantly incorrect papers on IQ that try to deny these factors and paint the IQ of non-white countries as low, with the only explanation being their “inferior” race/genetics I think the more important point we need to remember is that even if we were to discover that some groups have a genetic predisposition for higher IQ (putting aside the controversial nature of IQ to begin with), those with predisposition for lower IQ are still human and thus still owed what is due by virtue of their basic human dignity. It's also possible that over time, adaptation would change this predisposition. Populations aren't static.

skybrian 11mo ago

I don't fully understand this blog post, but possibly of interest: https://theinfinitesimal.substack.com/p/the-missing-heritability-question https://theinfinitesimal.substack.com/p/the-missing-heritabi... In particular, see the third chart, "GREML-WGS heritability estimates," which shows that heritability for height is pretty much the same when they try to adjust for environment in different ways, while the estimates for IQ vary a lot. Gusev seems convinced that some environmental effect is inflating heritability estimates for IQ that are based on twin studies.

delichon 11mo ago

> It means that in the United States nutrition has mostly been solved Nature is not off of the table. We've just traded problems with calorie quantity to quality. condition US prevalence hypertension 49% obesity 40% metabolic syndrome 40% prediabetes 38% fatty liver disease 25% diabetes 16% coronary disease 5% That's not mostly solved, that's tens of millions of truncated, immiserated lives. Of course calorie quality differences are important to child development.

tptacek 11mo ago
I think you'll find in comparisons of 2025 to the turn of the 20th century that we lives are, by comparison, neither truncated nor immiserated. Anyways, this has nothing to do with the topic of the thread.
- delichon 11mo ago
  My argument is that we cannot simply say, they're both getting enough calories, therefore we can discount the nutritional component of their IQ differences. Sufficient calories do not remove nutrition as a confound.
  - tptacek 11mo ago
    You're handwaving away the nutrition hypothesis for the Flynn Effect, and I think losing sight of the timeline for the comparison. It's going to be very difficult to make any case like this if we're looking back to 1900, which is what we're doing when we talk about the nutrition/intelligence shifts we see in stats.
    - delichon 11mo ago
      We seem to be having different conversations. I'm responding to if we know for sure the genes are the same and nature is off the table, how much variance remains? ... and saying that nature isn't off the table at all. Are you saying that it is?

underlipton 11mo ago

>and therefore the only real differences that can remain are the genetic differences. Incidence of undiagnosed digestive and sleep disorders, like celiac disease and sleep apnea, respectively. "Catch-up" growth occurs almost universally after treatment starts, which means that the growth trajectory was lower than the "genetic potential", and likely remains so for children who can't access treatment. Multiply across any number of silent or untreated disorders, sensitivities, or insufficiencies. Adult height also isn't 90% heritable in the US. It only reaches that high a percentage of heritability in studies involving closely-related populations. In which case, of course; in populations with low genetic and cultural diversity and moderate or high variability, small differences are magnified.