Alcohol is one of the easiest trappings and snares that Satan has in place for anyone , especially teenaged kids, because of its easy accessability and for those over 21 it is LEGAL by the laws of the land.
It's ability to render our otherwise self control and disciple diminishes with the first drink. That's all it takes for most of us, is one tiny tear in our heart, to open a door or pandora's box, that may take years to close.
I agree with Whirlwind, we need to guard our heart and for me drinking was a sin as well.
The Good Lord will convict you in His Time as He did me, as you grow, strengthen and mature in your Walk.
Always remember that you are His Child! God is Patient, Loving, Longsuffering, Forgiving and in His Love He will admonish us when need be.