Bloggers like HBDchick and increasingly mainstream scientist and authors argue that the unusual history of (partly Church mandated) outbreeding, certain societal structures / customs and the steady replacement of the lower classes by the middle class has changed Europeans genetically to exhibit higher intelligence, more moral behavior induced by a stronger propensity for guilt, less nepotism, less violence and more empathy, altruism and trust for strangers than basically any non-European ethnicity. This is the putative origin of the WEIRD psychology.
I don’t know to which degree this is correct, but it is definitely not a non-starter. One can leverage a lot of data to show the trait differences of WEIRDoes compared to the rest of the world. There is some data to imply a genetic cause of the observed differences and the evolutionary stories at least sound somewhat plausible.
Now HBDchick is likely a lovely person with no bad intent, but her work can of course be used to argue for some form of white supremacy. This, however, quickly leads to a funny contradiction, which seems to me to be the central contradiction of white supremacy:
Along every dimension white supremacists are more like the rest of the world and less like the WEIRD.
They are less intelligent, to a degree that the right generally has a recognizable human capital problem. They abhor the „pathological“ altruism exhibited by their co-ethnics. They are certainly more violent and would have a hard time to argue for moral superiority. One could go so far as to say that Western leftism is exactly the quintessence of what makes Europeans different from the rest of the world!