I identified as an asexual when I was younger, just because I was so behind all of my friends in development. Instead of tapping my feet waiting around for something to happen, or worse, forcing myself into situations where I felt uncomfortable, I said “Okay, well, if that’s the way it’s going to be, at least for now.”
I believe it’s natural to occur, but yeah, it is different from the norm and average. If somebody views it as a negative, for example, they are in a marriage and their spouse wants to have sex, then it should be up to them to consult a doctor about it. For an outsider to judge somebody with no sexual attraction as an aberration (all negative connotations included) is just wrong. It just doesn’t lead anywhere good.