so to give an example of this that works in my culture. Any child born anywhere in the world can speak any language fluently. But if they are not exposed to certain sounds early in life they can learn to speak a language fluently but they will never pass as a native speaker. We all know such people. It is not because they were not born with a capacity to make those sounds, it is because they grew up early on in a world where that sound did not exist, and their brain essentially did not bother to develop the capacity to make it and the window closed and they can never make it when they grow up.