As a born and raised Midwesterner who moved to Bama more than a decade ago, I may be able to provide a bit of insight. (I grew up in Illinois. I didn't even know I was a Yankee until I moved here.
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Personally I think that in general the South believes in traditions alot more in all aspects of life. From Sunday dinner at Mema's (meaning Grandma, that was new to me) to "Every female in my family is/was an ABC and I'd be disowned if I even looked at XYZ". (Ok I know I'm being extreme, but I have seen some of these situations.)
Something else and this has strictly been my personal experience, but it seems to be much more common to hear someone from the North, Midwest or West say "I'm the first woman in my family to go Greek". Another thing to consider is that Southern GLOs generally are still growing in numbers while on many other campuses across the country Greek numbers are shrinking. I can't explain either of these. Maybe someone else could shed some light.