We have wild quakers in my area, and I'm always amazed at how different their calls are from my own quaker.
He was found as a hatchling when he fell out of one of their nests, so he's genetically one of them, but has never lived with another quaker. He was raised in a home where the only other bird was a GCC, and he never learned the "local quaker lingo." I take him for walks in a pak-o-bird, and he often sees and hears the wild quakers, and even so, he sounds totally different in his contact and alarm calls. (The two most common calls I hear from the wild group).