The segregated Mexican, the indigenous Mexican is easy to get, but if you want to get a nonnative indigenous Mexican you'll not get the normal white Mexican, there is a word in slang in Mexico that is called Whitexican, but if we use that word we get a really strange person, so that did not work, it kind of works 'White Mexican' sometimes you need to use Posh Mexican, some times you have to add weights toward other races, Spain, Japan, I had to use Japanese people to get to a portrait I needed to do for a famous Mexican, look around this is a strange page.
here is a way to get Mexicans with no hats to use this prompt
Mexican:: hat::-0.25
Mexican:: hat::-0.5
Mexican:: hat::-0.25
Mexican:: hat::-0.5