Also has a lot to do with how smart the original owners were. What they let him get away with.
if he's REALLY not very smart, then the intelligence has been bred out probably a QH or TB cross. The Nez Perce indians bred them to have good feet, to be intelligent, brave, easy keepers. But man has had to cross-breed for his own reasons, and bred out a lot of these qualities. However, the color on that horse is amazing. He's gorgous.