When I was about 14-15 or so, a lot of my friends were getting into popping dexies. I just had to ask my oldies who are both biochemists, what the fuck dexies were. Being a fairly clued up kid, I could absorb most of the info, which primarily related to the way amphetamines fuck with your central nervous system which governs much of peoples behaviour. This was enough to scare the living shit out of me, especially knowing that I used to be prone to things like nervous ticks as a little kid etc. Of course, the fact that I am a bit of a hypochondriac (sp?) helped, but regardless, I haven't had a dexie for a long time after that.
I hung around people that did drugs from about the age of 15 and was quite proud of the fact that I didn't smoke or do drugs - and they respected me for that. That all changed after I found out that a chick that I had a crush on for ages actually hated my guts

From then on I decided that I hated life, and got stoned for the first time. I was 17 I think. It didn't take me THAT long to get over it...well..., but by then, I was beginning to REALLY enjoy smoking bongs

I've tried speed when I was 18 and the rest when I was 19.
I agree completelly with Cowboy Mac in relation to the development of ones body. The effect that hard drugs may have on the development of a young child can be unpredictable. It must also be said that hard drugs may adversly effect the psycological development of a child leading possibly to complications during adulthood.