I've decided to split this into two separate posts (for reasons that, I think, will become obvious), so here's the first. The second will get here eventually.
First, I think we have to be careful when analyzing fetishes and other sexual preferences for several reasons. In part that's because fetishes rarely come from a rational place, and often times one doesn't even really understand the root of one's own fetishes, much less the fetishes of others. So if it's a fetish you don't share, it may be just downright impossible for you to understand, comprehend or make sense of said fetish. But then there's also the problem that even if you can break down a particular fetish and make some sense of its sources and appeal, your analysis is ex post facto. And as much as it may appear to be a coherent explanation, there's the potential for people to mistake it as the "reason" behind the fetish, as if someone made a conscious decision to adopt a particular fetish. And, indeed, it can be easy then to conclude that the "reason" behind the fetish is what really makes the fetish arousing for a particular individual, which may not be true at all.
Let's take an oft-argued example of a widely shared fetish, the shaved pubis. It's so widely shared, and essentially socially normative at this point in history, that many would hardly consider it a fetish, and some would even argue that being into the opposite is the fetish these days. Analyzing the shaved fetish leads many to observe that the shaved pubis resembles the pre-pubescent pubis, thereby suggesting that the attraction of the fetish is really about pre-pubescence. One potential logical conclusion is that men aroused by a shaved or bald pubis are clearly attracted to pre-pubescent girls and therefore must be pedophiles. That such men would ask or encourage fully matured women to alter their pubic hair in this way is their way of fulfilling their disgusting fetish, and the women who enable these men are simultaneously the sad victims and unknowing accomplices to this displaced pedophilia.
I think that's all wrong, but I purposely chose this example because there are plenty of people who follow their analysis to just such a conclusion. I would argue that what happens with this and many other fetishes is that some event occurs during a formative stage of our development that lights up our brains like a neon light, and like that first hit of a drug, creates an association that will last for years or decades. And, like the junkie, it's not that they take the drug again in order to relive that first moment, but rather to achieve that emotionally charged high that was, and maybe still is, associated with the particulars of that moment.
So, yes, in a way, the fetish of the shaved pubis is tied to pubescence, but to the man's, not the girl's. The fetish is embedded in a non-rational, subconscious way that the individual may not even realize or recall, and no matter how coherent or convincing the later analysis, it doesn't necessarily translate into a "reason" for the fetish to exist.