I suspect that environment has a lot more to do with that than innate capability. A two-year-old lives in a full immersion environment where the only language

I suspect that environment has a lot more to do with that than innate capability. A two-year-old lives in a full immersion environment where the only language they can communicate in is the one they are learning and where a large portion of the people they interact with are going out of their way to help them practice. They also have no responsibilities other than learning language and a few other skills. Put an adult in an environment like that and they will make extremely rapid progress.