This is a follow-up to my language-learning metaphor entry.
One comment was about the unlikelihood of mastering a "new language" (literally or metaphorically) if you only start learning beyond childhood or adolescence.
This seems to be a common view.
I always like to look for counterexamples (it's my mathematical way coming out in me):
1) the first one that leapt to my mind is Joseph Conrad, one of the greatest authors in the history of the Engish language. Conrad did not speak a word of English until he was 21. He began writing in English at age 32. His first published works came out when he was about 37. In order to learn English, he did not attend language classes or read grammar books, but chose to live and work in an English-speaking environment (immersion!).
2) I don't know much about rock musicians, but my research led me to a biography of Tom Scholz, from the group Boston. He started playing musical instruments at 21.
3) Here's a link to someone else's list:
4) Here's another list, which is part of a review of a book called Defying Gravity: A Celebration of Late-Blooming Women:
5) Another link with good examples:
(I'm the one who added Joseph Conrad to this list).
...I invite other suggestions to expand my list!