Finding normal?

How do we know what's normal? It's amazing how many friends I've had who, when talking with others, suddenly realized that what they thought was "normal", wasn't. Even bodily functions - yeast infections, celiac disease, hearing loss, ... It's amazing how often we take for granted, problems that are solvable. If we extend that into the differences in how people think or learn, we have an even wider field to play in. Where do we draw the line between "has trouble socially" and Asperger Syndrome? When do we decide that "I'm just not good at ..." vs figuring out that "I can do ... but only with this workaround." Only by communicating with each other, reading, sharing knowledge, do we learn not only what's "normal" but also what's *possible*.