Your culture stems from where you were raised, primarily up through mid-teens. it instills your commonly held speech patterns, and celebrations and observances.
Some, especially military brats are raised in a different location every 2-4 years and often don't form those 'cultural identities.
Often, people will adopt and/or substitute the cultural norms of their current location.
As has been mentioned, there is more and more blending across this great land of ours.
