You know, it does seem like this could be so. It seems like people of African-American descent experience stronger pressure for conformity and a lack of lofty expectations or idealistic visions in life. ST consciousness over NF. And I'm not sure, but it seems like brown-haired Caucasians and Asian-Americans are expected to be somewhat more intelligent/articulate than other people. A very slight NT-ish overlay, I guess (although the SJ overlay of society in general is stronger than this one). And it seems like Latino races are expected to be somewhat SF in demeanor.
Although I think these don't really affect who you really are, it could very well affect how you express yourself.
Just another thing to consider while deciding your type, I guess... think about exactly how you are mentally, try not to think about how you feel you should be.