marijuana and predispositions

Today I read an article that said that drug and alcohol use by people with developing brains (teenagers younger than 17) can activate a genetic predisposition to addiction. That's one of the best reasons I've heard so far for keeping kids away from, ahem, extraneous chemicals. However, I had a problem with the very last sentence, where it said that marijuana can cause schizophrenia in the same crowd. Like many of the under 40 set who have been exposed to years of US government bogus-sounding marijuana facts, I'd become conditioned to ignore alarming information about marijuana. (I still never tried it.)

So, I felt obligated to go look it up. Wandering around the internet, I found a list of articles on schizophrenia.com that pretty much agree with the above statement, but I didn't find anything that limited it specifically to people under 17. I also learned:

1. that the US government prefers to report that 80% of teenagers do not currently use marijuana, but other people like to report that 42% of high school seniors have tried marijuana,
2. that professors named Danielle or Daniele like to study drugs, and
3. how to spell schizophrenia.