Several cross-country examinations have found larger gender differences in Western countries. More recently, it has been argued, from an evolutionary standpoint, that equality may paradoxically increase gender differences, because it provides more freedom for men and women to pursue innate preferences. However, this paradox has primarily been examined with this cross-country methodology, opening up for other cultural differences to drive the results. For instance, measures developed in Protestant and Germanic-speaking countries, may not work the same in other cultural clusters of countries, and may not have the same statistical qualities there (e.g., in terms of reliability). Here, we reanalyze the results from multiple studies on the gender-equality paradox with country-level data available. We find that gender differences co-vary more strongly with cultural regions and data quality than gender equality, and that any variable higher in the West appears to achieve similar correlations as gender equality. Also, controlling for cultural regions consistently and strongly attenuates the association with gender equality, including to become statistically non-significant, or to switch direction. In other words, the baseline associations differ between and within cultural clusters (a Simpson’s paradox), suggesting there is no simple causal relation between gender equality and expressed gender differences. Similarly, controlling for data quality indicators strongly attenuates the paradox. Finally, we show that, with and without controls, there is no consistent paradoxical association across many of the largest cross-cultural studies on gender differences, including newly analyzed data. The same is true for other country development variables considered in the gender-equality paradox literature.