How tall you are depends on your genes, but also on what you eat, what diseases you got as a child, and how much gravity there is on your home planet. And all those things interact. How do you take all that complexity and reduce it to a single number, like “80% heritable”?
The short answer is: Statistical brute force. The long answer is: Read the rest of this post.
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How heritable is speaking Turkish?
Close to 0%.
Your native language is determined by your environment. If you grow up in a family that speaks Turkish, you speak Turkish. Genes don’t matter.
Of course, there are lots of genes that are correlated with speaking Turkish, since Turks are not, genetically speaking, a random sample of the global population. But that doesn’t matter, because if you put Turkish babies in Korean households, they speak Korean. Genotypic values are defined by what happens in a random environment, which breaks the correlation between speaking Turkish and having Turkish genes.
Since 1.1% of humans speak Turkish, the genotypic value for speaking Turkish is around 0.011 for everyone, no matter their DNA. Since that’s basically constant, the genotypic variance is near zero, and heritability is near zero.
How heritable is speaking English?
Perhaps 30%. Probably somewhere between 10% and 50%. Definitely more than zero.
That’s right. Turkish isn’t heritable but English is. Yes it is. If you ask an LLM, it will tell you that the heritability of English is zero. But the LLM is wrong and I am right.
Why? Let me first acknowledge that Turkish is a little bit heritable. For one thing, some people have genes that make them non-verbal. And there’s surely some genetic basis for being a crazy polyglot that learns many languages for fun. But speaking Turkish as a second language is quite rare, meaning that the genotypic value of speaking Turkish is close to 0.011 for almost everyone.
English is different. While only 1 in 20 people in the world speak English as a first language, one in seven learn it as a second language. And who does that? Educated people.
Most people say educational attainment is around 40% heritable (though we'll return to this later). My guess is that speaking English as a second language is similar. But since there's a minority of native speakers (where genes don't really matter), I'm dropping my estimate to 30%.
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Heritability can be high even when genes have no direct causal effect. It can be low even when there is a strong direct effect. It changes when the environment changes. It even changes based on how you group people together. It can be larger than 100% or even undefined.
Not really sure why, tbh. The LLM is responding in accordance with common human assumptions/misconceptions in the same scenario -- I too immediately assumed English's heritability would likewise...
Not really sure why, tbh. The LLM is responding in accordance with common human assumptions/misconceptions in the same scenario -- I too immediately assumed English's heritability would likewise be zero at first because I didn't take second language learning into account.
Oh, it had nothing to do with the mention of an LLM, and more to do with the energy of being right about something nuanced and misunderstood. The author could've said "Google" instead and I think...
Oh, it had nothing to do with the mention of an LLM, and more to do with the energy of being right about something nuanced and misunderstood. The author could've said "Google" instead and I think I would've had the same reaction to their phrasing.
As someone who occasionally talks about things that are nuanced and misunderstood, there are times where I probably should've just said "Some people will disagree with this, but I'm right."
Ah, yeah, that's a fair enough observation. It's a common thing to hedge a little when making claims, just in case you happen to be mistaken or have gotten something wrong (I know I do this a lot...
Ah, yeah, that's a fair enough observation. It's a common thing to hedge a little when making claims, just in case you happen to be mistaken or have gotten something wrong (I know I do this a lot myself), so it's refreshing, straightforward writing to not hedge at all and just say "I'm right." And in this case, I think the author backs it up enough that it pays off!
The article seems pretty good at math and thinking through unusual implications, but my armchair Substack eugenics alarm that I keep in the back of my brain is beeping. Saying that variance was...
The article seems pretty good at math and thinking through unusual implications, but my armchair Substack eugenics alarm that I keep in the back of my brain is beeping.
Saying that variance was "invented for the purpose of defining heritability" is technically correct, but that might not be the best kind of correct in this case, because it was invented bythe founder of the University of Cambridge Eugenics Society who had decided, presumably to support that project, that he wanted to define something called "heritability".
His particular formula for heritability is presented in the article as if it has odd traits but is obviously basically a sound thing to want to calculate, despite the purpose it was designed for.
The vigorous "educational attainment is 40% heritable, well OK maybe not but it's a lot heritable, stop quibbling" hand waving sounds like a person who wants to show but can't support a large figure. And that framing of education, as something "attained" by people, rather than something afforded to or invested in them, is almost completely backwards at least through college.
The various examples about evil despots and unstoppable crabs highlight how heritability can look large or small independent of more straightforward biologically-mechanistic effects of DNA. But they still give the impression that those are the unusual or exceptional cases.
In reality, there are in fact a lot of evil crabs, doing things like systematically carting away resources from Black children's* schools, and then throwing them in jail. We should expect evil-crab-based explanations of differences between people to be the predominant ones.
*Not to say that being Black "is genetic". Things from accent to how you style your hair to how you dress to what country you happen to be standing in all contribute to racial judgements used for racism. But "heritability" may not be the right tool to disentangle those effects.
From the article:
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Did anyone else get shivers reading this line? No? Just me?
Not really sure why, tbh. The LLM is responding in accordance with common human assumptions/misconceptions in the same scenario -- I too immediately assumed English's heritability would likewise be zero at first because I didn't take second language learning into account.
Oh, it had nothing to do with the mention of an LLM, and more to do with the energy of being right about something nuanced and misunderstood. The author could've said "Google" instead and I think I would've had the same reaction to their phrasing.
As someone who occasionally talks about things that are nuanced and misunderstood, there are times where I probably should've just said "Some people will disagree with this, but I'm right."
The kids today would call dropping that in a conversation/speech “aura”, I believe.
(/noise)
That's new to me. I only just learned bussin. I'm not ready for my five year old to grow up...
Ah, yeah, that's a fair enough observation. It's a common thing to hedge a little when making claims, just in case you happen to be mistaken or have gotten something wrong (I know I do this a lot myself), so it's refreshing, straightforward writing to not hedge at all and just say "I'm right." And in this case, I think the author backs it up enough that it pays off!
You said it better than I.
The article seems pretty good at math and thinking through unusual implications, but my armchair Substack eugenics alarm that I keep in the back of my brain is beeping.
Saying that variance was "invented for the purpose of defining heritability" is technically correct, but that might not be the best kind of correct in this case, because it was invented by the founder of the University of Cambridge Eugenics Society who had decided, presumably to support that project, that he wanted to define something called "heritability".
His particular formula for heritability is presented in the article as if it has odd traits but is obviously basically a sound thing to want to calculate, despite the purpose it was designed for.
The vigorous "educational attainment is 40% heritable, well OK maybe not but it's a lot heritable, stop quibbling" hand waving sounds like a person who wants to show but can't support a large figure. And that framing of education, as something "attained" by people, rather than something afforded to or invested in them, is almost completely backwards at least through college.
The various examples about evil despots and unstoppable crabs highlight how heritability can look large or small independent of more straightforward biologically-mechanistic effects of DNA. But they still give the impression that those are the unusual or exceptional cases.
In reality, there are in fact a lot of evil crabs, doing things like systematically carting away resources from Black children's* schools, and then throwing them in jail. We should expect evil-crab-based explanations of differences between people to be the predominant ones.
*Not to say that being Black "is genetic". Things from accent to how you style your hair to how you dress to what country you happen to be standing in all contribute to racial judgements used for racism. But "heritability" may not be the right tool to disentangle those effects.
I mean, they’re attempting to explain some rather unintuitive math. Getting into the sordid history of genetics would be a distraction.