Sheldon exhibits a strict adherence to routine, a total lack of social skills, a tenuous understanding of irony, sarcasm, and humor, and a general lack of humility or empathy. He is vocal about his own superior intellect compared to all around him. These characteristics provide the majority of the humor involving him, which has caused him to be described as the show's breakout character. Despite speculation that Sheldon's personality traits may be consistent with Asperger syndrome, obsessive–compulsive personality disorder and asexuality, co-creator Bill Prady has repeatedly stated that Sheldon's character was not conceived nor developed with regard to any of these conditions