I think we should be very careful in not having this thread spill out into a big flamewar about ADD/ADHD, which are legitimate and medically-recognized behavioural disorders.
The original post was a pretty straightforward question about whether an airsoft gun would be appropriate for a 12 year old, particularly one who is showing signs of behavioural issues. We're not doctors, but it doesn't take a doctor to answer this question with "it depends, and whatever the answer is, it must be answered with care and with the safety of the child in mind". I think that for the OP's purposes, we've adequately raised the warning flags here.
Now you know