Twin study suggests rationality and intelligence share the same genetic roots - the study suggests that being irrational, or making illogical choices, might simply be another way of measuring lower intelligence.

[u/mvea]

https://www.psypost.org/twin-study-suggests-rationality-and-intelligence-share-the-same-genetic-roots/

[u/DieMafia]

That intelligence is mostly heritable is not a bold claim, it is the consensus. Heritability also increases into adulthood, while the effect of shared environment decreases to almost nothing.

The results show that the heritability of IQ reaches an asymptote at about 0.80 at 18–20 years of age and continuing at that level well into adulthood. In the aggregate, the studies also confirm that shared environmental influence decreases across age, approximating about 0.10 at 18–20 years of age and continuing at that level into adulthood.

Source

Here is a very recent study with a large sample size (n > 14.000):

Genetic transmission, in turn, seems to be the primary mechanisms of intergenerational transmission of cognitive ability and becomes increasingly important with age.

Source

That IQ is heritable is not surprising, since almost any trait is. Here is a more general overview that was published in Nature Genetics and encompassed virtually all published twin studies for all kinds of traits with over 14 million twin pairs, of which a subset of >300k related to higher level cognitive traits:

Source

That intelligence is highly heritable is really not a question if you are at all familiar with the literature. IQ test scores of identical twins raised apart are almost as highly correlated as those of the same person tested twice, while scores of unrelated siblings raised together are almost not correlated at all.

[u/Draugron → u/DieMafia]

It is very funny that one of the conclusions of the source I gave was that the existing primary data was gathered using flawed assessment methods, and that the solution moving forward was to conduct more primary research using better methods, not more meta-analyses using corrected data from those same sources.

And the sources you gave in your responses were all meta-analyses using corrected data from those older, flawed primary sources.

[u/DieMafia → u/Draugron]

It is very funny that one of the conclusions of the source I gave was that the existing primary data was gathered using flawed assessment methods, and that the solution moving forward was to conduct more primary research using better methods, not more meta-analyses using corrected data from those same sources.

Your link is about the correlation between job performance and IQ. This has nothing to do with the heritability of IQ. That IQ is heritable is the scientific consensus and majority view, and the methodology for assessing the heritability of IQ has nothing to do with the methodology for assessing the correlation between job performance and IQ.

And the sources you gave in your responses were all meta-analyses using corrected data from those older, flawed primary sources.

This is obviously not true, since the sources I cited were not related to job performance (where correlations are corrected for e.g. range restriction) but were based on a twin study design. The second source I cited is a recent well-conducted primary study with a large sample size showing a large heritability of IQ.

[u/Draugron → u/DieMafia]

And yet you interpreted my disagreement with the statement that genetics are the primary determinant of intelligence as one wherein I completely dismiss all forms of the heritability of cognitive ability.

And your second study has yet to be cited for any further research, and specifically makes the claim that it is outside the common consensus. You'll forgive me for dismissing it until the broader scientific community can chime in.

[u/DieMafia → u/Draugron]

And yet you interpreted my disagreement with the statement that genetics are the primary determinant of intelligence as one wherein I completely dismiss all forms of the heritability of cognitive ability.

Where did I do that? Apart from that, the sources I cited all show the heritability of intelligence (in adulthood) is >50%. What is your definition of primary determinant?

And your second study has yet to be cited for any further research, and specifically makes the claim that it is outside the common consensus.

The study specifically refers to the conventional social mobility perspective in sociological research on the "intergenerational transmission of advantage". It does not refer to the view on the heritability of intelligence amongst researchers of intelligence or behavioral genetics, where substantial (e.g. >50%) heritability is the consensus.

You'll forgive me for dismissing it until the broader scientific community can chime in.

If you want an overview that probably reflects the general consensus of scientists in the field, you could take a look here: Genetics and intelligence differences: five special findings. Robert Plomin (the main author) is a professor of behavioral genetics and one of the most cited psychologists in general (>750 articles and >100k citations). Is that good enough?