Replying...
Intro. The Cuckoo sisters emerged from egg cells harvested from then-villain telepath Emma Frost, while she was in a coma after a sentry attack that killed her students, the original Hellions. In reality, they were only five of many cloned "daughters". The remaining hundreds (if not thousands) of clones, reside within the incubation chambers in a laboratory hidden underground in The World, a Project Weapon Plus/Weapon X housing complex. They were created by Dr. John Sublime to be powerful weapons capable of killing all mutants by combining their telepathic abilities. The Cuckoo were designated Weapon X. They all share the same mind with slight differences that mark them.

Cuckoos Sisters.

@Angel