Normal isn't a measurable thing.  It is what we expect.  We expect people to think, speak, and act in a particular way.  Abnormal is when a person acts differently than we expect or things work out differently than we expect.  Because normal isn't a definite thing or an absolute truth, it depends on the expectations of each person and what is considered normal depends on who is defining it.

Normal is boring and unenlightening.  I prefer abnormal.