Mm- I'm not sure.
This goes back to nature v. nurture, doesn't it?
IMO, the -ahem- damage is done very early on- even at conception if the mother is a) very young, b) drinks, c) smokes and/or d) comes from the sort of deprived, neglected background that engenders early promiscuity.
These DCs are born 'behind the 8 ball' iyswim. Whatever hand wringing, social equality pushing 'liberals' may think, this DC is likely to have a significantly reduced chance of what we measure as success in life. They are far more likely to end up 'known to the authorities', they are far more likely to lead chaotic lives, and are at great risk of repeating the cycle.
I feel what we as a society needs is stick and carrot.
Abortion and adoption at birth should be presented as a better option than it is for both the mother and the often, the DC's chances; the father should be chased via DNA and made to pay ( I imagine there'd be far more young men pulling on condoms if they knew their Social Security was going to halved in order to support their casually conceived offspring!); there should be more or less compulsory 'mother and baby' homes, not council flats for those whose own parents cannot or will not support and guide them.
As for removing a DC from the group, really they have to be removed from the entire environment that engenders such behaviours in the first place. You can throw all the 'resources' and teachers you like at the issue, but, as the Jesuits used to say, 'Give me the boy at 7 and I will show you the man'....
I recall 7 being about the age where certain (not all!) DCs at my DSs school from 'sub optimal' backgrounds stopped being 'You poor little thing' and became 'You little shit!' as their behaviour became more dangerous and threatening. Yes, again, I know I will be flamed for 'writing off' that DC at that age- but really, it's not that I am writing them off as much as the fact I have no powers to do the things that might possibly have prevented that potential human car crash of a life heading that way!
The people who perhaps could are far too ham strung by being PC and touchy-feely to tackle the problem at root cause.