Correlations between socioeconomic status and success of one's offspring in educational systems don't mean that intelligence is inherited in the genetic sense. If you're seriously arguing this, you're very close to flirting with eugenics and the like.
> If you're seriously arguing this, you're very close to flirting with eugenics and the like.
Please don't be so eager to reject eugenics that you end up being anti-science. The idea that some percent of intelligence is genetic is entirely reasonable, not something to refuse to consider.
I did not say nor mean to imply that genetics do not have anything to do with IQ or intelligence. Also, context matters - this is a thread about how to structure educational environments and about certain specifics of the military. Genetics are a factor that is going to be of limited practical use in this domain, at least as far as I can fantasize OTOH.
> I did not say nor mean to imply that genetics do not have anything to do with IQ or intelligence.
Please explain what "Correlations between socioeconomic status and success of one's offspring in educational systems don't mean that intelligence is inherited in the genetic sense." means because it sure looks like an argument that the genetic component isn't real.
Especially because you posted that in response to someone talking about heritability in very general terms, so your comment can't be interpreted as a nitpick about which evidence goes where. And I can't think of any third interpretation.
> this is a thread about how to structure educational environments and about certain specifics of the military
The idea being presented is that it's easier to run good schools when you have smarter students with smarter parents.
So the inheritability of intelligence over a single generation is critical to the argument.
Maybe what I actually meant to express becomes more clear if I re-phrase and expand the the sentence a bit:
Correlations between socioeconomic status and success of one's offspring in educational systems does not mean that you can determine genetics as a relevant factor when thinking about how to structure education and if one is interested in the relationship between success (on whatever metric) in education and family trees.
I'm neither a geneticist nor is English my first language but I've always understood "heritability" to be a term that very much has to do with genetics and the Wikipedia link you provided implies the same. If we are talking about other factors/mechanisms that impact success in educational systems and that express themselves over generations and in family structures - sure, that's basically what I'm saying.
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(Long) edit after a cup of tea and a sandwich spent over the Wikipedia-Link you provided:
I must say, I think that's pretty readable even for me as a non-geneticist. In the context of this thread, there is a lot of interesting info about "Heritability and caveats", "Influences" and "Environmental effects". I've highlighted these quotes for myself while reading:
"Although IQ differences between individuals have been shown to have a hereditary component, it does not follow that disparities in IQ between groups have a genetic basis."
"Heritability measures the proportion of variation in a trait that can be attributed to genes, and not the proportion of a trait caused by genes."
"Contrary to popular belief, two parents of higher IQ will not necessarily produce offspring of equal or higher intelligence. Polygenic traits often appear less heritable at the extremes."
The whole section on "Implications":
"Some researchers, especially those that work in fields like developmental systems theory, have criticized the concept of heritability as misleading or meaningless. Douglas Wahlsten and Gilbert Gottlieb argue that the prevailing models of behavioral genetics are too simplistic by not accounting for gene-environment interactions. Stephen Ceci also highlights the issues with this assumption, noting that they were raised by Jane Loevinger in 1943. They assert that the idea of partitioning variance makes no sense when environments and genes interact and argue that such interaction is ubiquitous in human development. They highlight their belief that heritability analysis requires a hidden assumption they call the "separation of causes", which isn't borne out by biological reality or experimental research. Such researchers argue that the notion of heritability gives the false impression that "genes have some direct and isolated influence on traits", rather than another developmental resource that a complex system uses over the course of ontogeny."
Since this is a US-centered forum, this also seems relevant:
"In the US, individuals identifying themselves as Asian generally tend to score higher on IQ tests than Caucasians, who tend to score higher than Hispanics, who tend to score higher than African Americans. Yet, although IQ differences between individuals have been shown to have a large hereditary component, it does not follow that between-group differences in average IQ have a genetic basis. In fact, greater variation in IQ scores exists within each ethnic group than between them. The scientific consensus is that genetics does not explain average differences in IQ test performance between racial groups. Growing evidence indicates that environmental factors, not genetic ones, explain the racial IQ gap."
> Although IQ differences between individuals have been shown to have a hereditary component, it does not follow that disparities in IQ between groups have a genetic basis.
This is just about race & IQ and already cedes the genetic argument that you were refusing to believe - because the evidence is so overwhelming.
> Contrary to popular belief, two parents of higher IQ will not necessarily produce offspring of equal or higher intelligence.
Not necessarily is load-bearing here in an extremely misleading way. Two parents of higher IQ are much more likely to produce an offspring of higher IQ than median.
You’re basically just cherrypicking arguments that support your incorrect supposition when compared to a mountain of evidence on the other side.
Why do you insist on saying that I "don't believe" in genetic components when I've literally said the opposite? The people who wrote the stuff on the Wikipedia site I was provided with and their (researcher-)sources seem to try to tell you and me both "hey, this is an interesting field of study but it's very complicated, many genes are involved, we are far from understanding them or being able to model them, be very careful with interpreting correlations and for (m)any practical purposes (such as thinking about how to structure educational environments), you really should consider quite a lot of things not directly related to genetics." What's so controversial about that and what overwhelming evidence does that go against?
edit: Sorry, to clarify, you are saying that "Two parents of higher IQ are much more likely to produce an offspring of higher IQ than median" because of genetics as the main determining factor?
> "hey, this is an interesting field of study but it's very complicated, many genes are involved, we are far from understanding them or being able to model them, be very careful with interpreting correlations and for (m)any practical purposes (such as thinking about how to structure educational environments), you really should consider quite a lot of things not directly related to genetics."
I'll say the same thing as you: context matters. Someone trying to say that smarter parents lead to a smarter student body doesn't need to model any genes and they don't need to care about the difference between things that are transferred genetically and things that are transferred socially.
> because of genetics as the main determining factor?
Does that matter? While the word "heritability" was used, and that term "very much has to do with genetics" as you say, that person didn't directly mention genes and didn't attribute any particular percent to genes. The original argument is the same whether genes are 80% or 20%.
Again, the person I was originally replying to called intelligence "highly heritable". That does mean a genetic argument and I replied to that and not a generic assertion that there are mechanisms in play that have influence on the expression over generations.
Absolutely agreed. I got bogged down in the genetics portion, but it is not actually a necessary component of the argument I'm trying to make - merely that kids are like parents.
you’re not arguing in good faith and now you’re motte-baileying. you said:
> Correlations between socioeconomic status and success of one's offspring in educational systems don't mean that intelligence is inherited in the genetic sense. If you're seriously arguing this, you're very close to flirting with eugenics and the like.
the obvious reading is that you do not believe in a genetic component to intelligence - and in fact say that a belief in “this” is arguing for eugenics.
> Sorry, to clarify, you are saying that "Two parents of higher IQ are much more likely to produce an offspring of higher IQ than median" because of genetics as the main determining factor?
Even if you remove all environmental factors, two smart parents are more likely to have a smart kid than the counterfactual.
My original answer was a condensed and far from comprehensive one-sentence reply to another condensed one-sentence-reply (that included the phrase "highly heritable" which is how the whole genetics argument started). Why is what you apparently perceive this original one-liner to mean so important to you? I've expanded on the points I was trying to make quite a bit. And again: The researchers who look at those things seem to be the ones telling us that the relationship between intelligence and genetics is complicated and many, many non-genetic factors are in play, no? Did I miss some big new movement on deterministic genetics in education or some such since I've sat my basic biology, psychology and sociology courses? Do you know stuff that's not on Wikipedia? Help me out here, please - and I'd politely ask you to refrain from insulting my good faith.
I'd also be - again, genuinely - interested in how you come up with that clear of a statement about smart parents and their non-externally-influenced child, how one would approach that as a research question/design and how - practically - useful this piece of data in and of itself would be when most of us are not Kaspar Hauser or any other conceptual model of a human being that exists without external interdependences.
> Why is what you apparently perceive this original one-liner to mean so important to you?
Well because you basically accused most people of being eugenicists simply for believing something that is most likely true and clearly implied a strong position that you are now retreating from. It's clearly an incendiary one-liner where previously the conversation was not so.
> The researchers who look at those things seem to be the ones telling us that the relationship between intelligence and genetics is complicated and many, many non-genetic factors are in play, no
There are massive biases in academia that encourage researchers to hedge results like this. When you ask anonymously, the answers & beliefs are clear.
> Snyderman & Rothman (1987/1988) — mailed survey to ~1,020 academics; 661 replies. Experts overwhelmingly agreed that IQ has substantial within-group heritability, and among those willing to give a number, the average estimate was ~60% for U.S. populations.
Also https://pmc.ncbi.nlm.nih.gov/articles/PMC4804158/ which is going to be a lower bound because it focuses on international differences.
Adoption studies pretty clearly upper bound the amount that these complicated non-genetic/non-prenatal factors can be causing differences in tested adult intelligence among Americans.
> I'd politely ask you to refrain from insulting my good faith.
Again, you started your entry into this conversation by leveling accusations of eugenics. The responses you get are going to be tinged by that.
> how you come up with that clear of a statement about smart parents and their non-externally-influenced child, how one would approach that as a research question/design
Adoption studies can provide an upper bound (excluding pre-natal environment). Also GWASs paired with mendelian randomization can provide a lower bound.
No, I said one is "close to flirting with Eugenics" wich is rather not the same than accusing anybody of being an Eugenicist and I stand by that point. However, you and the other person insisting on (mis-)interpreting my original one-liner now seem to do the "retreating" and to say that the post I was replying to somehow "clearly" was about the generalized notion of kids being like their parents instead of being very specifically about genetics.
The study you linked is interesting but its results are far from "clear" (see its discussion section but that's probably also just bias and hedging or whatever) and it does have fuck all to do with your proposed thought experiment of a Kaspar-Hauser-like child. Even less so with your confident prediction of how a Kasper-Hauser-like child would turn out. I think you probably know this yourself but these kinds of predictions are something scientists would very, very rarely do - because they know the limitations of their work.
I'm kind of weirded out by this exchange, people here rather confidently express quite a bit of stuff that goes against years and decades of training I received when I became a scientist and I think I'll stop replying now. That was the recommendation of a colleague - who actually is a geneticist - I showed this thread to over coffee as well.
> your proposed thought experiment of a Kaspar-Hauser-like child
Oh my god this is the most malicious possible reading of "remove all environmental factors".
They're talking about making the environments match, for fuck's sake.
The bulk of your comments are arguing that heritability is very complex, which is completely compatible with the words "highly heritable". And you still haven't explained why the term "eugenics" was relevant to anything anyone else said. If it's something about race, a superficial similarity across millions of people in shifting groups has very little to do with the correlations between child and parent that share 50% of their genes, but even if those were the same the comment still didn't say anything that got anywhere near eugenics!!
> the post I was replying to somehow "clearly" was about the generalized notion of kids being like their parents instead of being very specifically about genetics
I didn't use the word "clearly". You're misquoting now too?
And I still believe they meant the entire complex mess you're talking about, yeah. I think you have zero justification to barge in and say it's a complex issue, and the person making a single sentence comment must have meant the most simple possible version, there's no way they were referring to the entire complex issue already without your help, in a context where the distinction doesn't even matter.
Even if you're done replying I hope you see this: If you were actually talking in good faith you're doing a very bad job at giving anyone the benefit of the doubt for how they word things.
seems like a disbelief in heritable intelligence (absurd) is drawing some to use the US military as a shining star of schooling innovation without strong evidence. so seems clearly relevant and useful in this domain to identify which interventions actually work and which are just composition fx
What do you think "the heritability of IQ" means? It seems from the thread that you believe it's genetic causation of intelligence. Is that what you're claiming?
I think that's how zevon interpreted it, so that's what I responded to.
Personally I would include other methods. And for the argument about schools method doesn't really matter.
Edit: And I don't know if genetics are the biggest factor in single generation inheritance, especially at a younger age, but I do think they're a reasonably significant factor after looking at various estimates.
Right, just so we're clear that heritability isn't genetic determinism; it's a correlation statistic. All sorts of things are heritable that are absolutely not fixed by genetics. And there are things fixed by genes that aren't meaningfully heritable!
Of course it's not determinism but it is statistically causal. The point is the distribution of the student body is going to be different in a pretty significant way.
You said correlation, I said "causal" because it's going from parent to child.
"statistically" meaning any individual child could have any IQ, and genes are only one factor out of many, but when you measure the entire group the graph of IQs is going to look different.
A comparison would be like, filtering IVF in 50 couples based on X/Y chromosomes and measuring height. That filter doesn't decide how tall a child will be, but it does shift the average. The filter would cause a height change, on a statistical basis.
This is all very fuzzy. "Heritability", of the sort that we have numbers from peer-reviewed articles on, means something specific, and that specific meaning is not genetically causal.
That wiki page lists a lot of evidence that a meaningful chunk is genetically causal. Is there a strong reason for me to think otherwise? Even the pessimistic numbers from gene mapping that are cited are .1-.2
I mean, start with the fact that it's a correlation statistic and not a causal statistic and just work your way back from that. Heritability --- of the kind with a research literature cite record --- is simply the ratio of phenotypical variation to genetic variation. The number of fingers on your hand is not, in that statistic, highly heritable.
I don't think there's a Wikipedia cite that's going to get you over that speed bump in your argument.
A lot of those studies work very hard to split apart the genetic (and sometimes including epigenetic) factors at point of sperm meets egg, the environmental factors in the womb, the parenting factors, and/or the rest of the post-birth environment. They're not doing a simple ratio.
And to the extent that research successfully isolates the genetic factors, we know it's not some outside factor causing a correlation, and we know it's not IQ causing genes. Anything isolated there is genes causing IQ.
I think you should take a beat and read up on assortative mating; also on heritability, which is a population statistic, not a measure of any single person. As it stands, this response you just wrote doesn't make sense.
If you just measure genes and IQ, then assortative mating screws up that statistic very badly.
When researchers do studies specifically designed to isolate different factors, it's different. Please stop ignoring this part of my argument!!
Assume the most extreme case of assortative mating possible. Every child inherits two genes that list the exact IQ of its parents.
Do those genes correlate with the IQ of the child? If they do, there's only a few ways for that to happen. The causal factor could be how they're parented, or the environment, or the genes themselves. If you correct for the first two across a statistically large sample, and still see an effect, then it must be the last one.
> not a measure of any single person
I know. I'm saying each data point inside the statistic is arrived at in a specific way. Cause and effect only go via certain paths. It's easy to make mistakes about cause and effect by forgetting about paths, but you can categorize them and only some paths are possible. Any statistically resilient correlation has a cause somewhere.
Molecular and behavioral geneticists absolutely, in modern studies, attempt to deconfound heritability statistics. Within-family and sibling regression are two of those techniques. When you use those study designs, heritability plummets for IQ, but not for traits like height.
I'm not trying to stake out a position about whether IQ is in any sense genetically causal or fixed. I'm saying that it's much more complicated than the Wikipedia page on "Heritability of IQ" would suggest. That's the only reason I dipped into this thread. You can believe whatever you want to believe, but this is an actively (indeed, furiously) studied open question, and the answer is definitely not "twin studies from 20 years ago set a heritability number that resolves the question".
I know it's complicated, but you seemed to be arguing pretty strongly that the genetic component is zero which while possible is not well supported by the evidence.
If you're not trying to stake out a position then you did a very good job of convincing me otherwise.
I don't know where I implied it wasn't complicated?
Also my original statement was just that it's "entirely reasonable".
I think if you read the thread history you'll see that I said nothing of the sort. But a conclusive answer to the question of how much direct genetic influence there is on intelligence (outside of disease/disability genetics) is very much not supported by current evidence. It's an open question. Right now: it's not looking great for the hereditarians (define them as "there is a very strong genetic component to cognitive ability"), but that could change as molecular genetic methods improve. Nobody knows.
you seem to have taught yourself explicitly incorrect intuitions about how the world works, why? the vast majority of people know that kids resemble parents, it seems extreme to believe otherwise.
