Splice

Elsa and Clive, two young rebellious scientists, defy legal and ethical boundaries and forge ahead with a dangerous experiment: splicing together human and animal DNA to create a new organism. Named "Dren", the creature rapidly develops from a deformed female infant into a beautiful but dangerous winged human-chimera, who forges a bond with both of her creators - only to have that bond turn deadly.

She's not human...not entirely.