Sorry, I know this sounds a bit journo-ey, it's not, just based on discussion with DH tonight really after musing. DS is only 8 and while I'm in no way worrying or even really thinking about this right now, it might come up so may be worth thinking about, however briefly.
(To try to explain a bit better). DH reckons that most teens will go through a phase where they want to rebel/feel generally like nobody understands them and their parents are so awful, sometimes due to crap stuff at home but also sometimes just in response to normal boundaries. And that if this happens to coincide with them finding someone/something which validates that - whether it's dodgy friends, drugs, unhealthy relationships, or a disneyfied dad or whatever, they will tend to go in that direction inevitably, rather than the phase being a normal teenage phase.
I think I agree with the first premise (that most teens will go through a phase like that) but I'm not sure about the second (that if they have an opportunity to run with it, they will). He's seen it happen in his family, which is where he's coming from, whereas I'm going on instinct more than anything.
I suppose I'm interested to see what others think and whether you think there's anything that can help prevent a situation like this occurring.