Disclaimer: I’m not a neurologist, sexologist, penologist, or psychologist, although I was once a social worker.
The way in which pedophiles differ from other people is not that they are sexually attracted to children but rather that they remain sexually attracted to children long after they are no longer children themselves, and that they do not tend to experience sexual attraction to appropriate adult people but instead are mostly exclusively attracted to children.
The injury done to children by child molesters is not that children are exposed to sex but that they are subjected to coercive sexual experiences, which tends to ruin a person’s ability to select and enjoy healthy positive sexual experiences. What makes it coercive is the inherent power imbalance between an adult and a child. Even without force or threat of force or pain, the greater ability of the adult to plan and manipulate and misrepresent things makes consent invalid. But the damage done is not done because sexual behavior is inherently damaging to children, but because of the unequal power involved.
I have been a child, but I have not, of course, been all children. I know for sure that some children have distinctively sexual feelings and sexual interests, whether they act on them or not; I tend to assume this to be true of most children but I don’t know that, and I do hear many people describing their awareness of sexuality and sexual feelings as only beginning at puberty, so there may be a range of difference there. I can tell you that the sexual feelings of children tend (at least for some of us) to be towards other children — our peers at that time.
A child molester may be a person who had not-unhealthy sexual feelings towards other children when a child, who somehow got “frozen” rather than continuing to be attracted to people roughly the same age as time goes by. Something traumatic may have taken place to create that “freezing”, or the complexities of adult sexuality may have proven unnavigable for some reason, leaving memories of childhood sexual feelings as recollections of some “better” form of it. I don’t know. But I am leery of assuming, with no evidence, that it must be caused by a biological predisposition or propensity. There’s a trendy pseudoscientific inclination to attribute all differences in sexual expression to genes and biology. I say “pseudoscientific” because many of the people making those arguments are not making them on the basis of evidence but instead on the basis of having decided that it is politically desirable for it to be true. (And that in turn is based on the annoying and nauseating notion that in order for a non-mainstream attraction of any sort to be OK it has to be something that the people manifesting it have “no choice” about).
Another distinct possibility is that child molesters are people who find the power imbalance itself to be erotic. We live in the world that eroticizes power imbalance. Depictions of mainstream heterosexuality are rife with portrayals of seduction, sexual predation, sexual conquest, sexual dominance, and sexual possessiveness and objectification. If someone finds that a compelling erotic motif but does not experience actual adult opportunities as opportunities to have that kind of power over another as part of sex, children may represent an alternative where that power imbalance may indeed be found. (As I said before, that’s exactly what makes it wrong and impermissible).