Spoilers ahead. Plenty of familiar faces return in Jurassic World: Fallen Kingdom, including Chris Pratt's velociraptor wrangler Owen and Bryce Dallas Howard's park manager Claire. The film is even bookended by Jurassic Park's own chaos mathematician Ian Malcom, warning about the dangers of dinosaurs. But it's the new characters who have the most stake in the future of the films, and none are more key than young Maisie, the granddaughter of John Hammond's former business partner Ben Lockwood who was raised by the wealthy scion after her mother's death. Figuring out who Maisie's mom in Jurassic World 2 is unlocks a shocking surprise that changes the entire series.
Living in an enormous, isolated castle with only his estate planner, his granddaughter, and her nanny for company, Ben Lockwood's attempting to continue the work of his long-estranged business partner John Hammond, potentially rescuing the remaining dinosaur of Isla Nubar from a pending volcanic eruption. He and Hammond had an unspecified falling out years before Hammond opened Jurassic Park, and each went their separate ways continuing DNA research. It's clear Lockwood's as obsessed with dinosaurs as Hammond was, but his research went far enough that Hammond refused to continue working with him.
The key to that research turns out to be Maisie. Though she often asks Lockwood about her mother, who she was told died in a car accident, Maisie is never allowed to see the pictures of her. At one point her nanny, stunned to be let go by Lockwood's villainous estate planner Eli, stammers that she's always taken care of Maisie, of both of them. When Maisie finally does get her hands on her grandfather's photo album and finds a picture of her mother, she sees not a grown woman, but a young girl identical to Maisie. The line in the sand between Hammond and Lockwood was human cloning, and as Hammond succeeded with dinosaurs, Lockwood succeeded with his own daughter.
Maisie is a direct clone of herself. Like the dinosaurs taken from Isla Nubar and brought back to the estate by Eli, she didn't ask to be created, and yet exists, posing a living ethical dilemma. Eli lied to Lockwood about a rescue plan for the remaining dinosaurs, and has instead captured them to sell off to the highest bidder. Dinosaur DNA is an extremely valuable asset, and Eli and original Jurassic park scientist Henry Wu are working to weaponize it by creating a vicious, yet loyal and trainable velociraptor.
When some of the dinosaurs escape, a gas leak fills the area containing the remaining dinosaurs, forcing Claire to choose between stopping what Hammond should never have started and watching them die, or letting the dinosaurs escape into human civilization, with all the horrible consequences. That the dinosaurs have escaped each and every movie is a lighter version of this metaphor now made glaringly literal. Ultimately it's Maisie who frees them, saying "they're like me".
While she's not technically correct in that she doesn't weigh over a ton and isn't an apex predator, the science that made both Maisie and the dinosaurs is already out there in the world, and like it or not, humanity must confront what it's created. Again, as the technology for creating dinosaurs would continue to exist, perhaps letting the physical animals die instead of unleashing actual living creatures to terrorize suburban areas would've been preferable, but Jurassic World 2 is not that subtle. It's also paving the way for Jurassic World 3, when we'll likely have the opportunity to see humanity very literally deal with the mess its created.
The attempt to liken dinosaur and human DNA cloning capabilities to atomic power, for all the good and evil both can accomplish, doesn't quite hold up; the T-rex rampage of Jurassic Park 2 was terrible, but still doesn't match the damage of Hiroshima, for example. Perhaps when Jurassic World 3, slated for release in 2021, comes out, we'll see how Maisie's existence fits into the larger picture.