Accents just form in certain parts. And they're nothing more than how things are said. For example: In the south a common occurrence is that words like pin and pen sound the same to them. And when they say it it comes out as pin pin. Or in some cases they stretch the words to pien. And basically combine them. With the brooklyn accent I saw coffee more like cawfee. Or Dog more like dawg. Someone from boston might say cah instead of car. And accents are constantly changing. I just took a history of english language class. So accents came up a bit in it. But language does not make up an accent.