I remember as a child never wanting to do the stupid things my parents did when it came to smoking, drinking and the other kind of smoking. Once I became a Christian, they were even more out of the realm of possibility. Something changed when I was 16 and started smoking cigarettes. I found alcohol when I was 18. I found weed when I was 20 or so. I've since tried just about everything that didn't involve a needle. There were only a couple that were worth repeating.
The primary factor here is my children. I don't want to raise kids in an environment where they only hear no. I don't want my kids to do drugs when they are in school. As an adult, I don't care if they try something. It's the addiction that I'm worried about. I hope to raise my kids to make the appropriate judgement calls.
My wife has a different take. She was not an experimenter. She doesn't want my input or more accepting view points to be presented. She's probably right. Frankly it is our responsibility to guide them in the right direction. I'd probably just muddy the waters.
I think this could go on much longer, but because I'm still not solid on my stance, this isn't a soap box I should perch on.