Meta-Ken

In response to the comment "Marijuana makes you grow breasts" - I didn't have a chance to check out the NPR link, but this sounds like the old "Marijuana causes a drop in testosterone levels" argument (I don't believe anything else would cause a man to develop breasts other than a sharp decrease in testosterone and a corresponding increase in estrogen). Further research has shown that pot smokers do not experience any significant long term changes in hormone levels ( see this or this or this). There is a minority of reports which suggests a short-term reduction (measured in hours) of LH/testosterone levels, but these seem to be a much higher doses than normal.

Check out this site for a good overview of many of the myths out there about cannabis.