>>"Nothing you do as a child of less than 12 should affect the rest of your life as a result of government action. Punishment and/or treatment should be swift, finite, and essentially unrecorded."
I'd basically agree with that.
It's just that keeping DNA/fingerprints on file in the short term could potentially lead to swifter punishment for children who repeat wrongdoing.
What happens with records later is a tricky issue.
Someone who has done something seriously bad when very young but seems to have learned from the experience shouldn't necessarily have it hound them for the rest of their life.
It's easy to imagine some dangerous-but-basically-daft things that kids do and generally get away with having serious outcomes simply as a result of bad luck, or things that could have ended reasonably benignly escalating to something awful as a result of just a tiny lack of self-control.
However, when there's someone who seems to be an unrepentant serial (and likely future) offender), does it make sense to discard some or all of their records when they hit a certain age?