Hi Tung! Glad I am the first one to check your essay!
I can't give you great advice as I think you forgot to mention what the prompt is......
I think your first sentence is a little awkward. Make it: Fifteen (not 15) is the age of........in one person.
For instance, parents should decide
Try not to use hypothetical examples. Mention things that actually happened to you (make some up if you want but keep them realistic).
probably become corrupt
it should be "probably becoming corrupt"
By and large this looks like a SAT essay. If it is then it's really good!
If it is for college, however some specific examples of children making wrong decisions should help.