dude its simple. know where you get your pot. i know exactly where my weed comes from. straight out of the sc mountains or the club in sf. if you can prove to your mom that you know where its coming from, there shouldnt be a problem. and come besides, no one laces anyway. what would be the point? think about it...dealers run a business. they want profit, and customers. if they lace your weed with rat poison or some fucking rediculous thing that like, yuor probably going to die, and your friends will eventually figure out that your dealer sold you bad weed ( i have never ever heard of anything like this happening btw). look at this in the eyes of your dealer. he now has a VERY bad reputation of killing a kid. how much business does he have now? none...i duno man. coming clean is always the best thing but your the only one who knows your parents, do what you think is in yuor best interest.