Blinking eyes. some says it's mannerism.?

Many causes: Excessive blinking has many possible causes. Dry eyes, stress, habitual causes are possible. If the blinking is severe enough to interfere with activities, need to consider more significant problems like blepharospasm if both eyes affected, or hemifacial spasm if just one side of the face is affected. See an eye md to rule out simple causes, and see if further testing is required.