The question is... how many instruments can a talented 16-year-old play well, realistically? For the record, the boy started with the piano at the age of 3. Personally, I knew a few kids who could play three instruments well, but that's about it. I tried to search a bit, and all I found was something in a Guinness World Records book about a guy who played 108 instruments at the same time, 19 of them being melodious instruments. I'm not sure it's entirely helpful, since I'm assuming this guy wasn't a teenager.
And if we're already at it... what's the world record for the number of records a single person can play? I don't intend for the boy to break this record when he grows up, but I'm interested in knowing what's the limit.