How Many Bell Curves Are There?

How many bell curves are there to make it normal? And do you have to be inside all of the normal bits of the bell curve? Or just some of them? How many is some? There's that line that people draw with the diagnosis? So visually in my head, I've got loads of bell curves, like one in front of the other. But we're constructing this disorder on norms,. A variety of norms that are constantly shifting and changing That people need to be in a certain amount at a certain degree.