Complex sentence: They prevail among the region's visible cultures, but not everyone who lives in Acadiana is culturally Acadian or speaks Cajun French, nor is everybody who is culturally Acadian or "Cajun" descended from the Acadian refugees.
Split into simpler sentences: They prevail among the region's visible cultures, but not everyone who lives in Acadiana is culturally Acadian or speaks Cajun French. Similarly, not everyone who is culturally Acadian or "Cajun" is descended from the Acadian refugees.