MATURE enough to ask??

Today a student..
let me simply describe him first,
i) no manners
ii) doesnt respect teachers
iii) arrogance
iv) sucks in his MATH

ask my manager a question,
why are they so childish, can't they be more mature and less childish??
(with his eyes staring at a 4 and 6 years old students)
my manager kindly replied him,
u can't expect children not to be childish right?
then he walked away unsatisfactly..

tHere I went into thinking,
why would u ask that question?
is that a proof that u are already mature?
or ACT to be mature??
when all ur attitude towards ppl showed that u're a childish one..

WHAT is the proof to show that u're mature enough??
until today until now,
i still dare not admit that i'm mature..