When a top-secret program attempted to recreate the original Weapon X experiment that created Wolverine, the scientists involved failed to secure a test subject that could survive the bonding of the virtually unbreakable metal adamantium to their skeleton. Using the only available genetic sample from Weapon X, which was damaged, they were unable to salvage the Y chromosome after 22 attempts. Raised in captivity, X-23 was trained to be a weapon.