I have 2:
17 yo only interested in computer gaming
16 yo slightly more interested in the outside world, eg geography/science but not particularly actively. Otherwise, computer gaming like his brother.
Neither are interested in clothes, phones or sport.
Neither can think of anything they want.
Younger one might read occasionally, has a liking for popular classical music (but can download what he wants from the pc) and has at times expressed an interest in owning a knife
- I think he means a penknife - and a three cornered hat 
Sigh. Yes life with them isn't easy! Any ideas? What are you getting your equally difficult 16/17 yo (if you have one)?