Why do the Mannings sound like they have a Different accent ??

That is utter BS. New Orleans was founded in 1718, and the Church has been there the whole time. I am not sure how the time line with Brooklyn's development (http://en.wikipedia.org/wiki/Brooklyn) coincides with NO's, but the notion that nuns affected the accent of an entire city is plainly ridiculous.

http://en.wikipedia.org/wiki/Yat_(New_Orleans)

LOL. Yeah, she was probably pulling my leg. Besides, she lived in Metairie, which, as we all know, ain't really New Orleans proper.

Formerly an Irish enclave, Brooklyn became gradually became increasingly Hispanic in the 1960s-70s.