This article draws from anthropology, psychology, and history to gain insight into the causes of large-scale psychological variation among humans. The authors of this study are mainly concerned with the way that weak kinship structures induced by policies of the Western Church in Europe may have resulted in the modern "WEIRD" (an acronym for "Western, Educated, Industrialized, Rich, and Democratic") psychological profiles in that same region. By correlating the amount of contact with the Western Church, rates of cross-cousin marriage (as an element of kin tightness), and degrees of individualism (as an element of WEIRD psychology), the authors are able to find support for this theory.