You're really on to something here, Tigersha..
Just looking at my own little town in the USA, the effect of culture and environment are tremendously noticeable.
The other kids I went to school with from grades 9-12 have now all grown up and gotten very diverse lives for themselves. I haven't myself, for various reasons (whole other story), but when I correspond with them, the effects of culture are striking.
My former high school consists of two primary populations, White Suburbanites and White Rurals. We did have two "token" black families... who were pretty much just "White Suburbanites with Really Good Tans". So we can rule "race" right out.
Between the two populations.. The "White Rurals".. whom we call "rednecks".. primarily have jobs working at gas stations, doing manual labor, or, if the individuals possess a certain level of drive, have furthered their education and gone into the skilled trades.
The "White Suburbanites", whom we call "yuppies", primarily have gone on to have jobs in the Corporate sector..IT, Business Management, Accounting, Medicine, and Education.
Yet it's only the "Weird Kids".. who were called "freaks".. that you can actually have an intelligent conversation with. Those "freaks" were the oddball outcasts who didn't fit into either the Redneck or the Yuppie groups. They had their own interests, pursued education more more heavily in the main, even informally, and acquired a depth of experience and erudition that allows them to be decent conversationalists and thinkers.
Members of this tiny minority have gone on to become Academics, Entrepreneurs, Artists, or, like me, "Professional Weirdos".
This is all from the same school.
If you correspond with these individuals online.. somewhere like Facebook..the differences become immediate in terms of language. There is an increased difficulty for linguistic analysis in such a system, as some members of both main demographic groups have resorted to "text-speak" primarily as a result of accessing Facebook only via a mobile device..
But the Rednecks, for instance, almost constantly use hideous misspellings, "text-speak", and brutally poor grammar, resulting in difficulty parsing what they're trying to communicate.
The Yuppies, on the other hand, tend to spell better, but exhibit high levels of mistakes with contractions, and a slightly exaggerated tendency towards substituting "b" for "be" and "u" for "you".
Curiously enough, the Freaks show very little tendency towards shortcuts, misspellings, or grammatical improprieties, other than the occasional lapses one would expect to find from an educated person. Even more curiously, they tend to adopt proper spelling, punctuation, and sentence structure even when sending text messages.
Everyone being discussed here grew up within 20 miles or so from each other, yet I can clearly see the delineations between these groups even now, 20 years later. To my mind, this strongly supports your theory, and raises the question "What can we do about it, as a society?"