Accents are amazingly contagious.
My wife picks them up in a very short space of time, even when they are alien to her.
Me, with a London background, lost a lot of my East End vernacular at grammar school, and my mother's influence to talk proper.
But, anecdotally, I caught the Welsh valleys accent indirectly, by marriage, the wife's family coming from that neck of the woods.
I happened to get a few weeks of consultancy near Newport and stayed in a local pub.
I was very quick to slip into the "tidy", "there's lovely" and "duw, duw", chat.
Son's in-laws are farmers up in the hills above Barnsley, so I am greeted with "Aaaaaaaaah, ow do?", when visiting.
Here in wild West Spain we are immersed (integrated) to the extent that our daughter, a fluent Spanish speaker and in Madrid, chuckles at our campesino (country folk) corruption of Castellano.