May I ask why, specifically, you're asking about a son? Would you be fine with a daughter smoking weed?
I have 1 daughter and 3 sons. I have never smoked weed in my life, and I wouldn't want my children smoking it either (I'm aware that by TSR standards that makes me boring, and a terrible mother, so help me God I don't care
).
At the moment they're a bit young for me to be concerned (my eldest is 9) but at some point I intend to speak candidly with them about the proven effects of cannabis causing paranoia and so on. There's plenty of scientific research out there to back up what I intend to discuss with them.
Of course I shall also tell them about the medicinal benefits for people with specific illnesses, but I shall have a conversation about why it's not appropriate to use medication when you don't have that illness, etc.
I'll go into the temptations they'll be faced with - peer pressure, friends saying it feels good, and so on, because I don't want to just sound like "weed is bad and there's nothing good about it" as that could make them think I'm a liar if their mates are telling them it feels fab. So I will touch on that point, but I shall reiterate that the negatives outweigh the positives, citing examples and showing evidence.
I will engage with them in interactive discussions about it, not just sit and lecture.
If done
properly rather than just in a "I say NO" kind of way, it's not impossible that it may have a lasting impact and they may not take drugs. Not a guarantee of course, but as I've never taken them myself, I hold out hope that the apple might not fall far from the tree.
At the moment, I think my 9 year old daughter probably won't, but my 7 year old son (who is a complete sheep and VERY susceptible to peer pressure) might succumb to taking drugs. The other two I don't know yet.
I can only do my best.
Incidentally, I'll tell you what hit home about drugs for me. Not weed related, but rather heroin (which obviously is nothing like weed) - but it was enough to make my mind up that I wasn't going to take any illegal substances, ever. It was in May 2000 when a 21 year old girl named Rachel Whitear who died of an overdose hit the newspapers, and her parents made the decision to release a photograph of her body to the press, curled up in the foetal position, all purple and awful looking, with a syringe in her hand.
I was 16 at the time, just taking my GCSEs, and until that point I'd obviously had PHSE lessons in school about the dangers of drugs and so on, but it was only an abstract concept until then. Seeing that girl's body though like that in the papers chilled me to the core.