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/Sinai]

It doesn't take much reading between the lines to see that the author thought the very suggestion of general intelligence and rationality being anything but highly correlated was absurd, and did this study because of that.

“1) We found that irrationality, far from being what IQ tests miss, is one of the best IQ tests available. 2) We found that irrationality, far from being unrelated to genetics and more of a mindset, is among the most heritable of psychological traits. 3) Irrationality is making mistakes which are unnecessary: wrong decisions when we have all the information we need, and some simple logic means there is no reason for the error. We found that realizing what information is available, and applying some simple logic, is almost all of the cause of cognitive irrationality. 4) Cognitive ability explained nearly all of cognitive irrationality, and much of the overlap was genetic.”

[u/Tricky_Condition_279 → u/Sinai]

I think there are many other studies that back this claim. I won’t say they are universally unbiased, yet previous work has linked intelligence scores to tendency to engage in superstition, conspiracy-thinking, and entertaining supernatural beliefs.