I think the main problem with Marijuana is people over analyzing it. You can find a study that finds in favor of both opinions just like most things. (religion,etc.)
The thing that really bothers me is these studies give parents crazy ideas and they relay them to their children. If you tell a kid that Marijuana will "kill them", "make them go crazy", "make them addicted", and "ruin their life" than what happens when they figure out for themselves that it is not true? I'll tell you. They will remember you telling them the same thing about Heroine and Cocaine and figure you were wrong about that too. The LAST thing you want for your kids is for them to underestimate the power of these drugs! (trust me, I know)
It is better to tell them the truth and not exagerate it at all. They will find out later and "crying wolf" by putting Marijuana in the same category as hard drugs will only hurt you and them. And if it means that one day they experiment with Marijuana then it's not a big deal. It's harmless. The only real downside to it is lack of ambition. If this teaches them to stay away from the real drugs then you did the best thing for them.
I am not throwing out my opinion when I don't know what I'm talking about. The first time Heroine was put in front of me I remembered what they taught us in school about it. But, they said the same thing about Marijuana and I tried that and it was no big deal. So, since they said "all" drugs were the same and they "all" were just as bad I figured "Well, they were wrong about the weed so..."
I wish, so bad, that people would have been honest with me about drugs because I would have never tried the hard stuff. It led me to homelessness for 5 long years as a Heroine addict. I'll remember every night I slept on the sidewalk in the dead of winter for the rest of my life. I've been clean for over 5 years now but I am very lucky. Everyone else either died or are still out there.
So, when I think back to before all that started, the one thing that always stands out is the fact that we were told that all drugs are just as bad and they all are addictive. Please don't let your kid one day think to themselves "Well I smoked weed and never got addicted so..." THAT is the LAST thing you EVER want going through their head.
Be honest and don't listen to these "studies". I studied more than they ever could and I'm telling you how it is.
Save your children from that horror.