There is data to support Kanazawa’s claims about IQ scores and the relation to liberalism and religion. Studies from the National Longitudinal Study of Adolescent Health support Kanazawa’s theories. They found that young adults who describe themselves as being “not at all religious” have an average IQ of 103 during adolescence, while those who identify themselves as being “very religious” have an average IQ of 97 during adolescence.
In terms of liberalism, young adults who identify as being “very liberal” have an average IQ of 106 during adolescence while those who identify themselves as “very conservative” have an average IQ of 95 during adolescence. It is worth noting that both the description of very religious and very liberal is subjective, and means something different to each participant in the study.