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

I was born and raised in NO East and moved out of the city (to Houston) when I was 13. I don't have and never had a lick of accent, although I can interpret pretty good. I even went to Lafayette for college for 6 years and I don't have the accent. Now, I can do a pretty darn good voice impression and pull it out of the air as if I have been speaking it all my life.
The biggest influence in a person's accent is their parents and extended family.
Peyton and Eli had a Mom and Dad who watched over them growing up and were heavily involved in their lives. That's why their accent is traced back to a Mississippi one.

Archie was the greatest ever when I was growing up leading the Saints to the first ever break-even season. Can't blame a guy for that!