Good catch. Additionally, one of the authors on this is just a student at UWisc, and the other author is also not a professional researcher but instead an author of popular books.

This is not an ad-hominum, but does put into question the statistical training backgrounds of both of these authors to accurate assess the data.

The language is consistent with ESL writing, in my experience.

The strange thing is that the corresponding author and the co-author appear to be english speakers, as far as I can tell. I googled the primary author and found a YouTube channel where someone by the same name speaks clearly about neuroscience. Maybe I'm looking at another person with the same name and middle initial who also happens to speak about neuroscience and brain development?

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.

I don't fully understand this blog post, but possibly of interest:

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.

> 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%

>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.

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.

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?

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_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). For example, a Danish white supremacist named Emil Kirkegaard went so far as to create a fake journal (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/) that has been widely retweeted by supremacists on X.

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. :)

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The other side to this is non-identical twins, especially when still very young and have had basically the same experiences (doing everything together), they can be very different.

If you give the same test to different people under completely different reward conditions, nobody is going to be surprised when the results are different.

IQ tests are far from perfect, but when the same test is administered to different groups under the same conditions it can be reasonable to draw some signal out of the differences between groups.

Generally in a study like this the people administering the test wouldn't even know which group each person belonged to.

It's common knowledge that IQ tests aren't perfect, but your linked paper doesn't debunk their usefulness in a study like this. Not unless the researchers unblinded themselves and offered one group a large reward, which would be a much bigger problem than the use of IQ tests.

I would guess that people will do better on just about any test when given a reward for good performance.

which will bias all correlations towards zero, while height measurement is very accurate.

yet iq inheritability is only a bit lower, around 80%

Of course. IQ tests measures nothing more than the ability to pass an IQ test, which is proxied by a lot of things such as western culture, education, propensity to cram tests, etc.

We don't know.

Define "more exposure to education". ;)

Also, NCBLA standardized testing has demonstrably ruined education in America.

More exposure to upper middle-class culture increases ones ability to take IQ tests.

I think it's inaccurate to call it a dumbing-down. It's more correct to label it as the largest stratification of education we've ever seen.

The smartest kids are smarter than ever before. They're absolutely rocking the house. The problem is that the "middle class has been gutted". Kids who were kinda smart, or kinda dumb, are now lumped in with kids who probably need Individual Education Plans (IEPs). This lowers the educational standard for almost all students - though of course the most well-off among us (educationally, rather than monetarily) are not only not suffering, they're thriving.

Sadly, this may be coming to NYC. In principle, I am all for trying to improve the baseline, but you cannot sacrifice better students to do that. Not only is it silly (how would this sacrifice exactly benefit worse students?), but unjust. Furthermore, education begins at home. Parents are the primary educators of children, not necessarily academically, but in the broader "life" sense. If the home environment is not conducive or supportive of education at school, you will be facing a very uphill battle.

The dumbing down of education goes further than what you note, though. Think of classical education and the formation of the human person (I'm not talking about "Dead Poets Society" ersatz, but the real deal). Think of the principles behind the trivium and quadrivium. In the best case, we are producing superficially technically savvy barbarians. Schools are effectively savage factories, and universities are laughable and should be ashamed of calling themselves universities.

On IQ tests, 15 points is a meaningful difference (one standard deviation), or roughly the gap between solidly average and clearly above average. It doesn’t make anyone a genius or a write-off. Still, we’d expect the higher-scoring person to generally find new learning and problem-solving easier, on average, if everything else is equal.

IQ scores are calibrated to be normally distributed with a standard deviation of 15. So 15 is one standard deviation. That's the difference between average, and being in the smartest 16% of the population. Or being in the smartest 16%, and being in the smartest 2% of the population.

15 points is significant difference.

If someone is 15 points above average, they are in 84th percentile, or in top 16%.

Well a sure component of test scores reflects test taking skills. Years ago, I purchased a book of a series of IQ tests, and my numerical result increased with every test. Another component is confidence. And another is ability. It is said by some that among the first big users of IQ tests was the US Army.

Well 100 would be your average person and 85 would be a person that has difficulty in school and at work with some tasks.

15 points is right around one standard deviation.

It's not nothing, but IQ is already a little squishy. No one's IQ is a single number. But the article also goes into problems with the study and other potential issues.

Basically, they're saying there is this pattern in the data as recorded, but there are multiple confounding factors and issues with collecting the data in the first place.

> A person with dyslexia, for example, will perform worse on these tests irrespective of their learning speed, learned knowledge, intellectual curiosity, or creativity. This is a form of bias.

No, it's what they were designed to do - help identify people that may need specialized help because issues like learning disabilities.

> To further complicate things these measures typically only account for academic intelligence. Other forms of intelligence include social intelligence, spatial intelligence, creativity, conscientiousness, and so forth.

The two major IQ tests (Stanford Binet and Wechsler) test visual-spatial reasoning, abstract reasoning, verbal and nonverbal reasoning, working memory, processing speed, inductive/deductive reasoning, attention, concentration, etc.

These tests, if properly administered (individually in person by a professional) work well for figuring out who in school needs extra attention or requires further evaluation. Their use beyond that is questionable.

This begs the question. How much of "intelligence" is intrinsic? We don't know. It's not zero (we know there are genetically-mediated cognitive deficits), but it's very plausibly not meaningfully intrinsic in most people.

How about the fact that the human mind and genetics are simply fascinating and interesting topics. I would imagine that people don't care as much about running and high school testing because they are fairly niche interests relative to abstract thinking in general, something that almost everyone spends much of their life doing.

There are many reasons. For example, there are large policy implications for schooling and education.

because then for the health of your offspring it's all determined by the wife you choose

but you can choose any wife and put it in an expensive school, be my guest!

Exactly, it is on of the least remarkable results that intelligence is partly heritable. Obviously intelligence is partly genetic, obviously your ability to run a marathon is also partly genetic. Why one has devolved into a bizarre case where so much effort is spent on the minute details of this question and the other is accepted basically as completely uncontroversial (given who is currently competing for top times at marathons it is basically inarguable) is very strange.

It is very hard to increase your own IQ score meaningfully by prepping to the test. That is why its a good measure.

Don't read this as a defense of Zuck or Musk, but some of the most brilliant people I've known sometimes had trouble getting thoughts out. It wasn't that they couldn't see their goal, but that how they thought of it was changing even as the words were leaving their mouths. Have you ever tried to explain while you were still working it out in your head? "See, it's kind of like A..., except that one part is closer to B, and that's interesting because, well, B and C have a relationship that's closer than A and C, so it might be more appropriate to say it's more C-like, except where A is..."

That didn't mean they were unintelligent. It meant that them trying to explain the flurry of ideas in their head was like me trying to type with mittens.

Of course, knuckleheads can also sound like that, but for different reasons. That kind of rambling doesn't imply that the speaker is a dumbass. It definitely doesn't guarantee that they're a genius.

I read the quoted sentence as "25 of the 52" -- not an additional 25 of the 87 -- because of the word "these".

52 pairs similar schooling 25 of these had very similar schooling

Thus the math becomes "87-52=35". 35 data points. Not spectacularly high regardless.

> With this said, it is important to note that the ‘very dissimilar education’ group consisted of only 10 TRA pairs. This small N is not a shortcoming of this analysis, per se. Rather, this is a shortcoming of the TRA field; these 10 pairs represent the entirety of individual data published over the last century.

Authors plead innocence!