what you are talking about has nothing to do with pedophilia. for one, the correct usage of pedophilia only refers to young, prepubescent children. being attracted to post-pubescent adolescents, teenagers and such (individuals that have mostly finished the physical maturation process - broad hips and bust in women, broad shoulders in men), is called ephebophilia, and is completely natural.
modern society has seen fit to lump it in with pedophilia, and for some reason 18 is seen as a magical age where 'OK, now it's socially acceptable to be sexually attracted to this person' but has no basis in biology or (nonrecent) human society. from a biological perspective, we are PROGRAMMED to be attracted to individuals in the mid to upper teenage years, because they are most likely to bear healthy offspring. given the variation that can occur in individuals reaching physical maturity, it can be damn hard to differentiate between some 16 year olds and 20 year olds.
For countless thousands of years, females were being married and having children at ages that would cause modern society to cringe, oftentimes to much older men, and it was the norm. Of course, recent advances in women's rights has probably had a lot to do with it, as now a female is treated as a human being with rights, as opposed to a piece of property that was to be married off for a dowry and social standing. but i digress.
actual pedophilia would be the case of a significantly older individual taking advantage of their position of power to sexually abuse a young, prepubescent child who is either unable to stop the attacker, or is too young/confused/scared to make a decision on the matter. it is ALWAYS rape, because the child can never give true consent, because they simply can't really understand what is going on. this has been shown to usually cause significant mental trauma and long term effects to the child, who is often made to feel guilty and ashamed of the whole thing, possibly repressing the memories to cause a festering canker of mental scar tissue that will stick around forever.
so... yeah. your anecdotes about horny young preteens and teenagers humping each other in the closet or hitting on older individuals is hardly relevant to the issue of pedophilia.