Yup. It's also complicated, and not sure any of us know the answer, but I think it's fair to say what people are attracted to changes through time anyway. I'm relieved to say now I'm middle aged, I don't really fancy 18yos. Not that I get the chance to test whether I'd turn one down(!) but as I get older, I find myself fancying people (roughly!) in my age bracket, with similar likes to me, similar cultural references.
So within that, I'm not entirely unconvinced that somebody can't be immature in their tendencies, and grow up and fancy adults... but I have no idea how you'd test that, and it might be utter bollocks!
In a 'normal' sense, most of us can resist our urges with people we're attracted to if they don't like us back, so *that* principle can surely be taught?
The problem in the instance in the OP appears to be that people ask for help, but often aren't given it *until* they offend... which seems bonkers to me, whatever the potential crime. I appreciate you have nutters who want attention, and tbf it must be hard to weed them out (if you come on here and say you have a massive desire to murder Mrs. Otis, at what point do we believe you?) but surely we should put in place some kind of procedure to see what help we can give people wherever possible?