This scene has been living rent-free in my head for a month and I have thoughts
"The word you're looking for is unnatural, meaning, not from nature... Freak, or monster, would also be acceptable."
(Dr Bashir, DS9 5x16)
I'm sure it's been said before, but the FEELS of this line-
To me, it sounds like Julian's reeling off a list of things he's been told he is. In any other situation, I'd assume he'd been bullied about his enhancements with these words and internalised them; but his enhancements were secret, so that doesn't fit here.
Which then made me think these are words Julian's collected from hearing about historical enhanced figures and then bullied himself with. Whether he heard them in a lesson, or in a friend's conversation, or even took it upon himself to research views of enhanced individuals, he seems to have learnt that genetically enhanced humans are freaks and monsters, and therefore so is he.
But I also looped back to the idea of his being bullied - (and I haven't watched past this episode so there may be something later to discourage this theory) - and I don't think it's too wild a guess to make that at some point he was. He's presented in the show as someone who just can't stop talking, who doesn't get social cues, who's "annoying"...it's not exactly a stretch to imagine a kid being bullied on those grounds.
(Nor is it a stretch to take these traits, among others, and headcanon that Julian Bashir is autistic. Many have, and it makes a lot of sense. And it works its way well into my little fiction.)
So as a kid, Julian is too smart and too loud and too eager. He has special interests coming out of his ears and learns everything he can about all of them, that's just the way his brain works. (That's what the teachers tell him, anyway, when some other kids call him names. They tell him lots of children are like him.)
((I can't decide if he's told he's autistic or not. On one hand, it's a convenient excuse for his parents to hide his extraordinary smarts behind. On the other, I cannot imagine them meeting the suggestion with anything but disdain and a snide "there's nothing wrong with our Jules", seeing as they're ableist af. But I imagine at the very least - with a little research and a couple of decent teachers - he must have had his own suspicions by the time he was a teen.))
I'm digressing - I apologise, at some point these thoughts became too long and meandering to be completely coherent. Right-
Too smart and too loud, his seemingly boundless knowledge is deemed as unnatural and freakish by his classmates. (When you're 7, any knowledge greater than your own seems pretty boundless.) And of course this was upsetting, and not easily forgotten. But as you grow, you do learn that people can be mean for little reason, and that whatever others think, it's perfectly okay for your brain to work differently.
Until you learn that it's not.
And here's where Julian Bashir realises that his childhood bullies were right about him. His academic abilities are unnatural and freakish (and, he will later learn, make him a monster). Because the line between "being able to learn everything that interests you because that's how your autistic brain works" and "being able to learn everything that interests you because that's how your genetically engineered brain works" is impossible to see. (Especially if your oh-so-caring parents take away the first option because "we made your brain perfect Jules, there's nothing wrong with you".)
Boy, that was a really long way of saying imagine if Julian was bullied for being autistic but ended up believing it was because of his augments and therefore that the bullies were right.