There have always been people who have had problems with the opposite sex, and while I dislike Freud in general, I think he identified this correctly: these people are immature, through no fault of their own, and their emotional development has been stopped at a certain phase as a result of outside influences.
For example, most girls go through a very intense "best friend" phase that is then transformed into a heterosexual focus, assuming their parental and other family relationships are healthy. Sometimes they're not...and a lot of these girls will never move beyond their 12 yr old phase. The phase becomes permanent, and they are then described as lesbians, which unfortunately now will be a title they will adopt with great delight because the press will love them for it. Still, they shouldn't be hated by the rest of us but should be treated with kindness, like anybody suffering from an emotional disorder.
It's when people start to crow and define themselves as "gay" as a permanent description that most of the rest of the population bails on them. Which is perfectly fine.
I believe it's the same with pedophiles. The very first girl I ever "fell in love" with was in the 6th. grade but so was I. My age preference for girls advanced as I did. Perverted minds are still stuck on that same age group that they were first attracted to.