That implies that this character was spliced to a living person. She only has extra arms, unless limbs carries the souls of people too. And note, in the backstory I have written in mind, these were fairly normal humans; no one of any particular unique ability was chosen, just anyone willing or available was experimented on. Those willing wasn't put through a mad science experiment so much as a rather mild-manner experiment operating on a very mad idea. It was free game on those simply taken, who were usually vagrants or wanders.