I meant fanfictions with secret siblings being the inspiration for Teresa's existence, if we counted fanfictions to include the ammount of secret siblings, there's probably enough of them to make an army lol.
If I know the mentality of people enough, I bet there's **** like, the sibling having spider powers somehow, being a better hero than Peter, other characters saying the sibling is a better hero than Peter even if feats aren't impressive (Or if they are, they're too impressive reaching ridiculous levels like that time Spidey beat Firelord), sibling being more loved than Peter, if it's a sister, Peter being overprotective of who she dates, and of course incestuous love, yep, did I miss anything?
I can understand the mentality behind that, people just want themselves to be in the story in some way, so even if a character is like the OC they're making, they'll use the OC because it's "themselves", it's also why those characters can/will become Mary Sues, though I'm not sure of the numbers of those who are/become one (I just assume it's very high lol), and chances are with a character like Spider-Man, he is a Mary Sue (Or whatever the male equivalent is) more often than not, which I assume it'd be to compensate for how bad his life gets, and do absurd things while they're at it lol.I am a fanfic writer, even I find the number of "long lost siblings" ridiculous. In my opinion, OCs should be used sparingly, and if there is a canon character who can play the role you want, use them.
Although, specificaly about secret siblings, just the very idea of it already irks me, it's a cliché that'll do that to me regardless of how it's used, like resurrection, though I can put up with it, hell, I even find Teresa to be an alright character, and while issue 2 of current Spectacular is by far the worst of the first 4 (And that's quite an achievement), it's not because of her, her part in that issue is actualy the best one, that really surprised me lol.