Unfortunately, you are wrong on so many levels.
The most racist of them all are the Thais themselves, especially towards their neighbors, but also towards farangs .
I don't know whether there is something wrong with the brain itself, but there is certainly something wrong with their IQ and their reasoning abilities. IQ tests have shown consistently that their average IQ is significantly lower than the average of 100.
It's also significantly lower in Isan than in BKK.That, of course, might be due to the educational system and poor diet, not the physical brain itself.
Then there is the Thai social character, an exceptionally high preoccupation with losing and gaining face, and the increased aggression associated with it, resulting in a high rate of violent crime. A Buddhist country it is, but in name only. One of the foremost Buddhist monks, the late Buddhadasa Bhikku said exactly that about his compatriots.
There might be nothing wrong with the Thai brain, but there is a lot of room for mental and characterological rewiring.