Major IQ differences in identical twins linked to schooling, challenging decades of research

Can't believe IQ is still a thing or taken seriously.

The idea that “IQ shouldn’t be taken seriously anymore” mostly comes from a misunderstanding of what IQ actually measures, not from any flaw in the science itself. It’s one of the most studied and replicated findings in all of psychology, and it strongly correlates with things like learning speed, academic performance, and even long-term health outcomes. It also survived the replication crisis better than nearly any other psychological measure and remains one of the most robust measures in behavioral science. The issue isn’t that IQ tests are unreliable - it’s that people often misinterpret what the scores mean. They don’t measure creativity, emotional depth, or moral worth - they simply measure a person’s ability to reason and solve problems relative to others.
- They don’t measure creativity, emotional depth, or moral worth - they simply measure a person’s ability to reason and solve problems relative to others.
  The frequent misunderstanding of what IQ means probably arises due to the vagueness of the term. "Intelligence quotient" is very non-specific, despite IQ measuring a very specific kind of intelligence. I wouldn't even say IQ measures "a person's ability to reason and solve problems relative to others." The problems found on an IQ test are of a very specific nature. "Complete the following number sequence", "Which of these shapes doesn't belong", etc.
  A problem that won't be found on an IQ test is: "Jeff believes his manager has made an inappropriate remark toward one of his colleagues. What should he do?" This is a problem that needs a solution, but isn't within the purview of IQ measuring. You mentioned that IQ tests don't measure things like emotional depth, which is true, but emotional depth (or emotional intelligence) is still intelligence, so the term "intelligence quotient" only referring to certain kinds of intelligence seems like it will naturally be misunderstood by the masses.
  I guess my takeaway is that the term "IQ" could use re-branding to avoid this problem.
IQ is not a completely useless metric. Yes it has its flaws and definitely shouldn't be used as an absolute scale of intelligence, but it can be useful to compare individuals and trends if used in the right context. We don't have many ways to test cognitive function.
This is actually the exact, singular purpose IQ is good for, and what it was initially created to do. It's definitely overused in society, but when you're trying to test a student to see how well their existing classwork has prepared them, it's a fine measure to use.

In any case, people should start viewing IQ testing as "cultural testing". We know it doesn't really capture "intelligence" but a western way of thinking about things. So basically some twins are more educated in western thinking than their siblings, and it has to do with their upbringing into the culture. Not surprised.

Math and spatial reasoning are western thinking? The only thing western about it is the language. I guess you could consider prioritization of math and spatial reasoning as western thinking but I think they would apply to anyone that participates in commerce which is basically everyone.
- Not necessarily the topic itself, but many factors affect IQ tests performance. Our perception and assessment of the world around us is strongly biased by our culture and education. The one factor you mentioned being the language is amongst many but its relevance should not be downplayed.
  I admit I wrote that comment being reductionist. Mostly because IQ tests and the conversation around them is often reductionist too, and lends itself to western elitism. The history of the study of intelligence is terrible and we should be better at dealing with the topic these days.
  Some examples of bias: https://neurolaunch.com/many-intelligence-tests-are-biased-in-that-they/ https://www.science.org/content/article/what-does-iq-really-measure

So ... what we've learned is that people with the same genetics will develop differently given different environments? Not exactly stop-the-presses news.

To the point where genetics is a rounding error is big news.
Yes. The issue is the accepted belief (among professionals) that "IQ doesn't change through life"... which is nice as a goal to develop a less biased "ideal IQ test", but also a really bad preconception when evaluating actual IQ test results.
There are many preconceptions like that in psychology, they need a periodic kick in the butt from actual data.
- I mean, in the past eight years, I've noticed my mental acuity sharply falling off. I'd imagine some hope for the future might turn that around, but I've been burned enough times that the high point of my day is usually hearing from the ex-wife I tried to kill myself because of twice.
Yeah I hate when there are funded studies to tell us the obvious. NewsFlash: Eating double the recommended calories make people gain weight.
- That's the whole premise of science though. To corroborate what we think is true with data. And more often than not it will turn out it wasn't even true in the first place.
  Your example is actually a perfect example of that, because no, more calories doesn't make a person gain more weight necessarily. This was thought to be true in the fifties, but then scientists checked again. And today we* know that it is much more complex how the body handles calories and when it gains more weight.
  well scientists know. The public knowledge hasn't been updated since the fifties really...
- Portion of those studies disprove the obvious, which is why they keep trying.

I'm in general very skeptical of testing IQ.

This seems like an appropriate use of it. Not as a general intelligence score (which is useless), but as a way to compare the environmental factors between 2 individuals.
- I disagree. The tests might indicate differences, but we cannot conclude its "major IQ differences". Because I don't think we can calculate the IQ, because that is not a single thing. It's like trying to put into scientific numbers how much you love a person.
  Note: To get the difference between 2 individuals, you need some sort of overall score for both. So you compare two useless scores to get a more useless score that only shows differences. And get a wrong conclusion about the IQ and such.
I fail to see how this is relevant to the article mentioned? I mean, IQ tests are reproducable, it's not like you will test significantly different now compared to a year ago.
- it's not like you will test significantly different now compared to a year ago.
  It does. Simple but important things like sleep impact it hard.
  I've had it assessed three times in a clinical context, and lowest was almost 10 points different than highest.
- My own experience is that you can get significantly different results when re-testing, even within a short time frame.
- Being reproducible does not mean the test is correct. I can reproducible do wrong math too.

What's frustrating is that this seems like it could be twisted either way with respect to the real prize this research is after: the extent to which intelligence is genetic, or environmental. Am I wrong?

I feel like it's pretty blatantly saying that it's not genetic, how would you twist it the other way?
- Because if different educations is the explanation for IQ differences, then that means that without external differences, the twins will have basically the same IQ. That makes it seem like, as long as you control other variables, twin IQ matches - what could cause that other than the fact they have the same genetics, now that other factors have been controlled away?
  But like you said, this could also be interpreted as indicating that education is the "sole" or primary determiner of IQ. This is what I mean by the right way to interpret these results being unclear.

So Tripping the rift - Nature vs. Nurture got it right: https://m.imdb.com/title/tt0865280/