Those were some of the leading candidates until twin studies and controls for familial wealth invalidated them and left us only with shminshmellishence :/
Wait, flesh this thought out? Twin studies were the dominant methodology of the 1970s-1990s, until molecular genomics --- and genetic studies with controls for family relations demolished their heritability estimates. You just wrote a sentence that implies a straight line of progress on understanding this (weirdly, giving a 70s-vintage point in one direction along with a 2010s-vintage point in the other), but it's the opposite (there's a whole thing about this, the "missing heritability problem").
"Go look up twin studies" is a very strange thing to tell someone on a message board in 2026. It's like saying "go look up phlogiston".
Identical twins reared together: .85 correlation in IQ
Fraternal twins reared together: .55 correlation in IQ
Identical twins reared apart: .75 correlation in IQ
And the genetic correlation grows as children age.
No, genetic studies did not "demolish" heritability estimates, they set a floor on them. Genetic studies do not and cannot (currently) predict all phenotypic outcomes, they set the floor on how much variation can be caused by genetic differences.
The genetic predictions don't even directly contradict, never mind demolish, the twin study findings.
The "missing heritability problem" is only a problem if one believes our genetic analysis techniques are comprehensive, but we already know they're not. For example, current methods are extremely limited in detecting gene-gene interactions, which we have good reason to suspect are widespread (otherwise making new genetic drugs would be trivial).
Yes, the .85 is probably at the upper end of the estimate. The genetic studies are the conceivable floor.
I'm not sure what you mean by "hereditarian" given that even the genetic studies obviously point to significant heritability.
This is always a funny conversation because on the one side you have people saying "intelligence is both heritable and correlated with nearly every outcome we care about."
On the other hand you have people saying "nuh uh! It's only... medium-high heritability and medium-high correlation with other positive outcomes," as if it makes any material difference to any downstream question.
It's not "the upper end of the estimate"; it's no longer the estimate. Meanwhile, hereditarians believe in strong genetic determinism for behavioral attributes. I think you should probably be more familiar with this field and its terms before being this confident about your numbers.
Again, the search bar will avail, but the answers you're giving here are very early-90s.
I don't know how we can continue discussing at this point, since "hereditarian" is not a slur (it's how many in the field would describe themselves). You either follow this research or you don't, either is fine, but it's not reasonable to attack other people for being familiar with it.
It's totally OK if we're just not going to persuade each other or develop any productive ideas in this thread! I've said all I originally wanted to say.
"Intelligence doesn't exist" is just a defense mechanism for above-average intelligence people to feel like they earned all their good outcomes.
But here's the thing: even if it was all hard work and not that you were born of above-average intelligence, it's pure luck that you were born someone who works hard.
But also intelligence exists and it's wildly discrediting to insist it doesn't.
You think there are people who are fortunate enough to have the desire to work hard, but nonetheless choose not to?
No, there's actually nothing convenient about the fact that most people are accidents of their genetic, geographic, and environmental roll of the dice.
The convenient view is: I worked hard because I chose to work hard. I achieved hard things because I worked to be smart. People who did not achieve the same things did not do so because they chose not to work hard or they chose not to be smart.
I did not say what your first paragraph says. I think there are people who do not have the desire to work hard, but who never the less choose to do so, even though they don't want to.
I will grant you that there are some people who, due to handicaps or other things beyond their control, do not have the option of choosing to work hard. But I claim (without statistical proof, I admit) that by far the majority of those who do not work hard, still have the real option of choosing to work hard, but do not.
For most of those who won't, "I can't" is also "very self-serving and transparently wrong."
