Complex sentence: While Lazarus is going through the rejuvenation treatments, his caretakers, Hamadryad and Ishtar, both give birth to female clones of him, their Y chromosome being replaced by an identical copy of the X chromosome.
Split into simpler sentences: While Lazarus is going through the rejuvenation treatments, his caretakers, Hamadryad and Ishtar, both give birth to female clones of him. Their Y chromosome being replaced by an identical copy of the X chromosome.