In Spider-Man: Into the Spider-Verse, we learn that Kingpin wants to find a replacement for his wife Vanessa and son Richard by using their DNA in the machine that opens holes into other universes. He uses a hair from a comb that gets put into the machine.
When Peter Parker as Spider-Man is fighting during the machine's power up, his head is pushed into the beam. I assume this is why other Spideys were pulled here - they share the same (close enough) DNA. Even Peni Parker could be a distant future relative in her universe, and Spider-Ham (Peter Porker) I can accept as being close enough in his animal universe.
But as far as Gwen, Spider-Woman, how was she pulled into Mile's universe?
We learn that her Peter Parker was killed long before. Why did a portal/hole open up near her when she would not share any DNA with Peter at all?
It can't just be the randomness we see from other universes, because we would have to assume there would be other (normal) people pulled in as well, not just Spideys.
Maybe I missed something, but it just seems like they glossed over a valid reason.