You can educate yourself and your parents about this but, as long as you are living under their roof, they still have the final say in the matter.

I don't think that anybody that is young enough to be "grounded", as you are according to another thread you posted, should be using the stuff. Even the most pro-pot organizations and knowledgable individuals believe that it's use should be limited to adults.

However, if you move out on your own you'll be able to do as you please.