My daughter (who is 8 going on 20) comes home from school and tells me that the teacher was talking about how drugs are bad,especialy pot.The whole thing got started when a kid in her class brought up that his parents smoke pot and that his parents had told him pot was not bad for you but good,needless to say I figured now was as good a time as any to explain what pot is and how it helps and how their are so many other things pot is good for other than smoking.I believe if you are stright with your kids about things and let them know its ok to come to you about anything.Like someone already said kids can pick up on bullshit a mile away and if you lie to them and they know it,it makes them want to dig deeper and not let it go,if they think your telling the truth and dont mind talking about it they usually move on,my kids also know tho that if me or my wife tell them dont bring something up in public keep it in the house and explain why,they will listen.
As for smoking in front of the kids (be it pot,cigirites) I try and avoid it and go outside or in my room or if I know their in there room I might smoke a quick 1 in the living room.Thats just me and I dont think anyways wrong really,everyone has their own family dianamick that works best for them that keeps everything moving along.