When a top-secret program attempted to recreate the original Weapon X experiment that involved the feral mutant Wolverine, they failed to secure a test subject that could survive the bonding of the virtually unbreakable metal Adamantium to their skeleton.
Seeking to take the project in a new direction, the project’s director, Doctor Martin Sutter, recruited renowned mutant geneticist Doctor Sarah Kinney and tasked her with creating a clone. Using the only available genetic sample from Weapon X, which was damaged, they were unable to salvage the Y chromosome after 22 attempts.
Kinney then proposed they create a female clone, and though her request was initially denied, she still went ahead and produced a viable female subject, prompting Sutter to reconsider.
Despite resistance from his protégé Doctor Zander Rice, whom he had raised after Rice’s father was killed by a bestial Wolverine at the original Weapon X Project, Sutter allowed Kinney to proceed.
As revenge for her insubordination, Rice forced Kinney to act as the surrogate mother for the clone, and she gave birth to “X-23.” More on Marvel.com