A common representation of youth is one of being let down by the adult world - be the parents, schools or authority. It's a representation that shows up in some unlikely texts such as Eden Lake, that from the trailer and a glimpse at the more horrific scenes, is pure and simply demonisation of youth (young = evil).
A closer look however sees the film continually try and lay the blame at the hands of the parents. The opening credit sequence has the young couple driving up the motorway while listening to a radio phone in discussing the problem of 'youth crime'. The callers continually pass the buck about who was to blame - the parents, the schools, the media - and so creates a representation of society unwilling to take responsibility. This is then expressed again when the couple express their concerns about the youths at the local cafe.
The final brutal scene really emphasises where the film places the blame showing that the gang of youths are just a product of the society and families they come from. In fact the groups of parents are represented in the much the same way as the demonised youths - casual sex, binge drinking, controlled by a bullying leader, resolve situations with violence. Brett is just fulfilling the same role as he sees his father take, and end shot of Brett posing in the mirror could be viewed as evidence that Brett partly knows he is playing a role. Find the clip on this post here. [SPOILER WARNING - THIS IS THE END OF THE FILM].
This idea of 'youths' just be a product of the society they are raised in is also, briefly, explored in Harry Brown. The only time we get a glimpse inside the minds of the youths and therefore get some explanation for their criminal behaviour is in the police interview room.
Again, just like Brett in Eden Lake, the Noel Winters character explains that he is just following his father's foot steps. We also learn that Marky is particularly vulnerable due to the upbringing in care he received.
Lastly have a look at this short film called Cherries, and count the number of times the youth are let down by the authorities and institutions that are supposedly there to protect them.