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Comment by tptacek | Hacker News Reader

The person who wrote that site spent quite a lot of time writing, yet unfortunately little reading. Heritability is, by definition, the degree of variation in a trait, within a population, due to genetic variation. The heritability of an accent is zero.

One clever way this is measured is twin studies, which also are not what most people, particularly those who prefer to write more than read, think. You don't search for twins separated at birth, but instead compare the differences in a trait between identical and non-identical twins. If the variation is greater, then the trait is generally significantly heritable. So for example - height would be an obvious one. By contrast the variation in accent between identical and non-identical twins would be zero.

The person who wrote that site is Cosma Shalizi, who very certainly knows what "heritability" is. Unfortunately, you appear not to. "Heritability" is simply the ratio of genetic variance to phenotypical variance. It's not genetic causality. Whether or not you wear lipstick: highly heritable. The number of fingers on your hands: not heritable.

So it's a blog from some guy with no background in genetics. Your definition is correct, as is your statement that it's not genetic causality. But to discuss heritability you need to understand the most typical, and reliable, way it's assessed. That would immediately clarify to you why lipstick wearing (or your accent) is not heritable, yet the number of digits you have (at least at birth) most certainly is. Here [1] is Wiki's take. You can also pick up any textbook on genetics.

[1] - https://en.wikipedia.org/wiki/Twin_study

I don't think "Cosma Shalizi doesn't know what he's talking about" is a good hill to die on, and you've now expanded your portfolio of opponents to Ned Block, from who I shoplifted the heritability point.

Direct genetic causality is not the only mechanism through which genes select for phenotypical traits. Genes also select and interact with the environment.

A person you respect in one field is not necessarily all-knowing within that field and, most certainly, not outside of it. This is especially true on topics that become politicized. This is not just because of the 'our side' vs 'their side' stuff, but because these issues can and have destroyed the careers of high profile people who adopt the wrong opinion.

Unlike the individuals you have cited, James Watson is a geneticist, spent his entire life studying and working on genetics, and in fact was even the person who discovered the structure of DNA. But because of his views on the genetic aspects of IQ (which inherently becomes intertwined into race, as race is just shared genetic ancestry), he was completely demonized, his career destroyed, and various honors revoked. Higher profile people speaking on these topics publicly know this all too well, so it mostly just turns into cheap virtue signaling as opposed to adding some genuine insight.

In your case, the examples they've offered are simply wrong, as would be immediately apparent with the most typical method of measuring heritability!

You're irritated because I gave you an output of the broad-sense heritability statistic that conflicts with your intuitive understanding of what "heritability" means. Now you understand how people feel when commenters randomly throw around the term "heritability" with respect to cognitive ability.

This is a "not even wrong" situation. Is cognitive ability significantly genetically determined? Maybe, maybe not. A broad heritability statistic from a twin study isn't going to resolve the question.

Here's a good link for you:

http://bactra.org/weblog/520.html

I promise, the author has studied and thought more carefully about the question than we have.

Fair warning: you would not be happier if I cited a molecular geneticist on this subject. Your argument gets even harder to sustain once you bring GWAS into the picture.

I'm not at all irritated besides the fact that you're relying on examples that simply are incorrect, and instead of responding to this issue in any way you're linking to walls of text from somebody who (1) has made plainly false statements on the topic already and (2) has literally 0 qualification in the field whatsoever.

It'd be akin to arguing to somebody who wants to claim the Moon landing was faked, and after the rather straight forward rebuttal of their argument links to some blog in the tens of thousands of words from some statistician they claim is "very smart." It's silly.

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