Of course, each of those kids can be cast a few years older without really effecting disbelief. First of all, I've never seen a comic anywhere that casts its characters as a specific age. The Power Pack is "young", Daredevil is "middle-aged", the Runaways are "teenaged" (which is at least more specific that the former two). Then there is the fact that many people are typically cast as characters who are 5-10 years older or younger than they really are.