ah - well this question has been asked by gawd knows how many people in the world...however...it does depend on how you think about this...
IF, and i do mean IF! if you decide to keep an "open" mind - just take a look through wikipedia and see how some groups/networks are actually campaigning for this sorta thing to be legalised! or atleast age of consent lowered to somthing insane!
its sick and screwed up if you ask me - how people can possible ever want to lower the age of consent is just...well its mind boggling isnt it?
how it happens? how someone turns into a peado? who knows? no one does to be honest. dont bother looking for an answer, youll find nothing but theory after theory.
BUT - and this is a big BUT - you MUST remember that their are female peado's out there as well. so dont single out men entirley as been 100% of the criminals.
are there more peados than we think? yeah there probably is. remember alot wont get caught or found out. the casual net porn surfer could download pictures all day and no one find out. you could have people abusing family members, and its all a big secret, no one finds out.
my advice though? dont contribute to turning this into a moral panic. its there, and it always has been there. until it affects you, - directly or indirectly - i wouldnt think about it