This research investigates whether 'birtherism' stems primarily from conspiratorial thinking or political orientation. Analyzing data from the 2012 American National Election Study (ANES), we show that while general conspiratorial tendencies influence some conspiracy beliefs, partisans and ideological self-identifications are significantly more important for explaining birther sentiment specifically.

Our analysis reveals distinct patterns:

• Partisanship explains belief in JFK assassination and 9/11 attack plots.

• Ideological orientation is the key driver behind 'birtherism' beliefs.

Conspiratorial thinking broadly, however, remains a significant predictor for specific conspiracy theories like JFK and 9/11 explanations.