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Small-Scale Question Sunday for May 7, 2023

Do you have a dumb question that you're kind of embarrassed to ask in the main thread? Is there something you're just not sure about?

This is your opportunity to ask questions. No question too simple or too silly.

Culture war topics are accepted, and proposals for a better intro post are appreciated.

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No, they don't. They rule out an argument that some part of the variation between identical twins raised together and apart is caused by the environment in the womb. But it does not rule out an argument that some part of the difference between identical twins born to a poor woman and identical twins born to a middle class person is caused by the environment in the womb.

They do rule out the argument that the variation between groups of identical twins of the same socio-economic class is caused by the environment in the womb, though.

Only if the correlation between identical twins of class X is identical to the correlation between identical twins of class Y. Is that what studies show? Because I know in other contexts the effect of genetics is mediated by socioeconomic status.

They don't need to be identical. The genetic correlation just has to be bigger than the SES correlation within a given SES group. Or you can just look at kids born to rich families but who got adopted out to parents of various classes.

It was my impression that this is what the studies, in fact, show. Maybe an earnest full-HBDer can give a link, I'm just a reluctant and partial one, that prefers the whole thing to be proven false.

They don't need to be identical. The genetic correlation just has to be bigger than the SES correlation within a given SES group

I don’t know what you mean by the SES correlation within a given SES group. Within each SES group, every kid is coded with the same SES. There is no variation in SES to use to calculate correlation, is there?

Regardless, if there is a difference between the pct of variation explained by genetics in twins born to low SES mothers and the pct of variation explained by genetics in twins born to high SES mothers, then that difference is caused by something, right? That is true even if the genetic correlation is enormous.

Or you can just look at kids born to rich families but who got adopted out to parents of various classes

Yes, but my question is whether such studies have ever been done.

I don’t know what you mean by the SES correlation within a given SES group. Within each SES group, every kid is coded with the same SES. There is no variation in SES to use to calculate correlation, is there?

There's still some income variation within a group, no?

Regardless, if there is a difference between the pct of variation explained by genetics in twins born to low SES mothers and the pct of variation explained by genetics in twins born to high SES mothers, then that difference is caused by something, right? That is true even if the genetic correlation is enormous.

Yes, but if the genetic correlation significant (doesn't even have to be enourmous) that already requires us to overhaul the way we talk about social issues. If you want to focus on the environmental things we can do to improve outcomes for people, go right ahead, but you can't presume isms because groups have different outcomes.

Yes, but my question is whether such studies have ever been done.

Once again, I believe so, but it would require digging through ages old SSC / TheMotte posts, or the materials of Kirkegaard / Sailer / Murray. I'm inclined to do neither, as I wish we could bury the whole idea.

There's still some income variation within a group, no?

Not if the point is to control for income variation. And, of course, SES is just a rough proxy for diet, drug and alcohol use during pregnancy, etc. The more fine grained the categories of SES, the less valid they are as proxies for behavior.

Not if the point is to control for income variation.

Isn't "middle class", or even subgroups like "lower-middle class", "upper-middle class", etc. still a pretty broad income range?

And, of course, SES is just a rough proxy for diet, drug and alcohol use during pregnancy, etc. The more fine grained the categories of SES, the less valid they are as proxies for behavior.

That doesn't seem to work to the advantage of your argument. Don't people clear basic pathologies like alcoholism and drug use after they get out of the lower class?

Isn't "middle class", or even subgroups like "lower-middle class", "upper-middle class", etc. still a pretty broad income range?

The question is the extent to which the behaviors I mention vary between the categories. To use SES as a proxy for those behaviors, you would want to look at how those behaviors vary by income, and construct income categories such that the categories act as decent proxies. If the mean person in the category "lower middle class" uses drugs once a week while pregnant, but the mean person in "middle class" uses drugs once a month, that might be fine (depending on what level of drug use is necessary to affect kids), even if the average person at the top of the lower middle class category is indistinguishable from the person at the very bottom of the middle class category (which of course is likely to be the case)

Don't people clear basic pathologies like alcoholism and drug use after they get out of the lower class?

I am not sure what you mean by "clear" - do you mean that they use drugs less when they move up? I am not sure why that matters; the question is how much they engaged in those behaviors when they were pregnant.