There is a show that might help you understand you DS a little better - its called "Whatever! The science of teens" - you can buy it from the ABC Shop (or if you have the time and speed, its on YT).

No-one and nothing can prepare children for the truth of Peer Pressure... Its not an external pressure that is the problem, but an internal extreme need to be accepted. Very interesting.. Some of the things teens would rather go without over their mobile phones is stunning.

HTH