So where does the innocence end? Does it matter if some 30 year old or 3 year old does a suicide bombing?
I'm not qualified to say (I'm not a father), but I think any kid under the age of six is a monster tolerated for the sake of continuing the human species. The age of accountability may come before that with exceptional children. The age of accountability may come far, far, far after that. But in general 6 years seems to be when a kid starts understanding things (and I think it's no coincidence that 6 seems to be a magical number for 1st grade.)