Too many interests means there is no interest

because you won't be able to spend valuable time in any one of the interests, and you are just using the activities to
1.kill time,  
2. to fill the void, to avoid boredem.  You appear busy and exciting, but in reality you are bored.
3. to please your parents.

kids should be allowed to get bored, to feel the boredem.  Boredem is part of life. Being able to face and overcome  boredem is an important ability. 

A word on rebellions:  If parents do not push, do not force value on kids, do not always to appear right, but just be a companion, a friend, a rival in games--there is nothing to rebel to. 

Allow/help kids to grow into and find their identity over the years, so there won't be an abrubt urge to find identity.  There is no need to rebel.