Well kind of. It's because you have not given them enough snacks. To change them back use the mirror. If you don't have one go to the Tips and Tricks Forum 'cause binarys got an info chart! Hope I helped.
Yes, it would be considered a "bad" thing. The Ninja Family is one of the neglected care families. You probably left it's hungry and happy hearts low and didn't train them when they called for it. Like Papapatchi said, use the mirror to change them back.
