Hello.

Marijuana has been proven, that if on a daily basis (once a week), weed will have no effect on you beside the fact that smoking anything is bad for you. Smoking marijuana on a daily basis will not stunt your growth or development (such as slowing down the process of hair growth). So, basically - if you smoke once or twice a week, I wouldn't worry about it. I have friends who have been smoking marijuana since their were 10 - 12 and are 18 - 21 and still toke. Their height ranges from 5'11'' - 6'6''. Their hair growth is fine, their gametes (sperm) is produced fine. Though if you smoke marijuana once a day, several times a day, ten times a week - you might want to start cutting down. Marijuana has only one affect on the body - the brain. It will kill thousands of brain cells. But if done on a daily basis, your brain will immediatley recuperate.
Ciggarettes stunt your growth, for sure - definitley proven true. The tobbacco contains something thats basically against hormonal development. Also alcohol...

So if you smoke marijuana a couple of times a week - don't worry about it, you'll be fine. Smoking marijuana is natural - 98% of Americans have been recorded on trying marijuana. My parents have smoked marijuana and thats why they were fine with letting my brothers smoke marijuana.