Everybody is different people. We all have a unique biochemistry to us, so different substances will have a different effect on us. Now, a vast majority of the population will experience similar effects due to the natural nature of the substance being used, but there are always free radicals to put into the equation. So what if the studies say that marijuana is not addictive - I've seen some of my close friends try to quit and it was like they were trying to get off of heroin (YES, I have seen people try to get off the shit, it is not pretty, nor enjoyable whatsoever). I wholly agree that MJ can become addictive. A scientific study cannot account for 100% of the human population due to the natural characteristics of our unique genetic make-up.