Are you annoyed by having almost 50% children, thanks to those darn migrant waves?
Are your food stocks in jeopardy because they're being eaten by hordes of useless twats?
Then this is the solution for you!
(Sorry if this is well known, but I saw a thread where someone didn't so I'm just making this. Yes, it's not as dwarfy as magma, but it's meant for starting forts)
The best way of dealing with children is, obviously, murder. How to go about this without discovery is a different challenge. But I have found a solution!
Dig out a 1*3 room, preferably near your dining hall, that is perpendicular to the hallway you're digging it from. Construct a door at the entrance, then a 2 long drawbridge that raises towards the far end of the room. Link these both to the same lever. But suspend the bridge, and dig out a tile adjacent to where it is when raised. Construct a wall in that square, and let the bridge be built and linked.
Designate the wall for removal. Check the jobs list to see if a child accepted it, if not, cancel it. (The closer it is to your dining room, the more likely it'll be a child as opposed to a hauler who just finished his job). When the child enters the room, pull the lever. The door will close, and 100 ticks later the bridge will atom-smash him where no eyes can see. Pull the lever again and the door opens and bridge raises, and the trap is reset for the next child.
I've been using this in many forts and it usually brings the number of children down to around 10 before it is more effort than it's worth getting them into the room instead of your mayor (Oh yeah, it works for him too.)
What do you think?