Because people grow up somewhere where people speak in that accent, and learn to pronounce words in a different way.
accents do nothing. They just make it hard for other people to understand you.
musical accent (the relative prominence of a musical note)
You can't reallyGET an accent, but depending on where you live might affect how you speak. EXAMPLE: If you live in Oklahoma, you might have a "Cowboy" or "Cowgirl" accent.
indiana In Marion County, Indiana.