I don't deny there's a genetic component and I don't believe stress is the single cause. I'm not well read on mental illness. But in the context of this story, stress was a cause (or trigger, whatever you want to call it) for a certain kind of behavior. It didn't seem like Giulia had any problems before her job.

"Some days, the stress of having to shower was too much. It was impossible to eliminate the stress enough since so much of it was misreactions to very low stress levels."

That's sad.