This movie stages action in a domestic and familiar environment, where violence never explodes, because violence is not a disturbance of that social order, but a pillar: it's behind every gesture, every word, every thought, it's something sinister always lurking inside the grownups (in a minor but important scene, during a birthday party the adults say horrible words towards a mother - but in whispers, like if they were haunted).
Parents shows and expose their kids as trophies, not caring for them but for themselves: in another scene a young father is pleased by the driving skills of his own son and proudly screams "You are like me!" - something that the kid is obviously not willing to be. Generations basically ignore each other's feeling: and ignorance is the trigger of silence, silence is the trigger of despair, and despair the trigger of violence.
Thanks to silence, conflict is invisible, and for this reason it becomes eventually inescapable: and the surprising epilogue is the only moment when peace is restored in the families, as the parents for the first time looks like they are actually caring for their children. We hear from the narrator at the beginning that everything in this story is at the same time true and false: and eventually we understand that this mix creates a scaring thing, called reality. This movie is good cinema and great advice, you should see it.