Inari wasn't a mutant by the same definition as those that Charles knew, but she wasn't strictly human, either. Her abilities, if you wanted to call them that, had been growing stronger, and she had very strong empathic leanings. And her brothers were still quite concerned that she might not be able to control them.
It wasn't the empathy that worried them, though. It was the ability to raise lust, and feed on sexual energy--and the ability to kill via touch.
So Inari tended to be a bit withdrawn when she was around people that she didn't know very well, which would probably show in her posture as she slipped through the kitchen, trying to be unobtrusive. She didn't want to attract the wrong sort of attention.