I on the other hand, use it towards my insomnia, as my uncle uses it for his bi-polar disorder, and my grandfather uses it to expand his creativity side for his architect career.
(I'm 19, a collage student, and get straight A's, and responsible)
but what I hate, is kids, who abuse the herb, and make ppl like me, my uncle, and my grandfather look down upon, for consuming the plant.
If your child is like that, tell him, to stop making a fool, out of himself, if he uses it for greater purposes, then have him be an adult and talk to you about it.
My mother knows and hates that I do it, but she also sees that I'm being a responsible adult who pays for all of my bills, and tuition as well.
Hope that helped at all.
Also on my behalf, may I reccomend a documentary, that will give you more info on cannabis.
The Union: The Business Behind Getting High.