She had a difficult adolescence, and it is implied, often by Sweets, that her withdrawn social tendencies are a defense mechanism. She also sometimes struggles in identifying and explaining her emotions, and takes comfort in the rationality of her anthropological discipline. Although it has been stated that Brennan was based on a person with Asperger syndrome, this has never been confirmed in the plot of the series. The creator of the series has stated that the character was never labeled as having the syndrome in order to increase the appeal of the show on network television. This influence on her character also helps to explain her extreme rationality in early seasons, as well as some of her social difficulties. Brennan is a self-proclaimed atheist and often points out what she believes to be the irrationality of religious and spiritual beliefs. This has led to more than one argument with Booth, who is a devout Roman Catholic; he becomes particularly irate when she compares less common religions, such as voodoo, to Christianity. During the "Sleepy Hollow" crossover episode "Dead Men Tell No Tales", "Sleepy Hollow" protagonist Ichabod Crane notes that Brennan is so skeptical that she would dismiss the demon Moloch — the primary antagonist in the first two seasons of "Sleepy Hollow" — as nothing more than a tall man with a skin condition, although this does leave him reassured that she will not realise the nature of the secret tomb they have uncovered underneath the White House.