We applaud Uchiyama and colleagues for their thoughtful and important contribution which marks a major step towards a culture-attentive, dynamic understanding of the genetic heritability of psychological and behavioural traits. In our commentary, we argue that an even richer and more comprehensive account of relevant sources of cultural influence can be accomplished by more explicitly considering geographical cultural layers within societies.

Like the authors and others before them (Cohen, Reference Cohen2009; Muthukrishna et al., Reference Muthukrishna, Bell, Henrich, Curtin, Gedranovich, McInerney and Thue2020), we are convinced that few societies are culturally homogeneous and firmly espouse the notion of culture as a construct that exists in many shapes and forms (e.g., religion and social class). Here, we seek to direct attention towards the multiple geographical layers of culture. The national level might be the most obvious and accessible geographical cultural layer. However, to capture the cultural space in which everyday life experiences occur, it could be valuable to consider more granular levels, such as regions (Ebert et al., Reference Ebert, Gebauer, Brenner, Bleidorn, Gosling, Potter and Rentfrow2021; Rentfrow & Jokela, Reference Rentfrow and Jokela2016), cities (Park & Peterson, Reference Park and Peterson2010), or neighbourhoods (Jokela, Bleidorn, Lamb, Gosling, & Rentfrow, Reference Jokela, Bleidorn, Lamb, Gosling and Rentfrow2015).

Thanks to the advent of big data, researchers now have the means to make these previously hidden cultural layers visible (Obschonka, Reference Obschonka2017; Rentfrow, Reference Rentfrow2020). Indeed, under the banner of geographical psychology, ample research has demonstrated pronounced intranational variation along cultural constructs, such as tightness–looseness (Chua, Huang, & Jin, Reference Chua, Huang and Jin2019; Harrington & Gelfand, Reference Harrington and Gelfand2014), collectivism (Talhelm et al., Reference Talhelm, Zhang, Oishi, Shimin, Duan, Lan and Kitayama2014; Vandello & Cohen, Reference Vandello and Cohen1999), and personality (Götz, Ebert, & Rentfrow, Reference Götz, Ebert and Rentfrow2018; Rentfrow, Gosling, & Potter, Reference Rentfrow, Gosling and Potter2008; Rentfrow, Jokela, & Lamb, Reference Rentfrow, Jokela and Lamb2015). Variation in such psychological constructs could affect variation in the frequency and type of cultural innovation that occurs (Harrington & Gelfand, Reference Harrington and Gelfand2014; Lee, Reference Lee2017; Obschonka, Schmitt-Rodermund, Silbereisen, Gosling, & Potter, Reference Obschonka, Schmitt-Rodermund, Silbereisen, Gosling and Potter2013). For example, regions high in cultural looseness and openness have been shown to have higher rates of inventions (Chua et al., Reference Chua, Huang and Jin2019), entrepreneurship (Obschonka et al., Reference Obschonka, Schmitt-Rodermund, Silbereisen, Gosling and Potter2013, Reference Obschonka, Stuetzer, Gosling, Rentfrow, Lamb, Potter and Audretsch2015), creative capital (Jackson, Gelfand, De, & Fox, Reference Jackson, Gelfand, De and Fox2019), and patent production (Fritsch, Obschonka, & Wyrwich, Reference Fritsch, Obschonka and Wyrwich2019; Harrington & Gelfand, Reference Harrington and Gelfand2014).

Importantly, subnational geographical cultural units are not only smaller than countries, but also more culturally nimble. That is, although cultural changes in the country-level typically unfold over decades and often centuries (Grossmann & Varnum, Reference Grossmann and Varnum2015; Inglehart & Baker, Reference Inglehart and Baker2000), regions or cities may experience considerable cultural shifts within shorter periods of time. For example, regional variation in the legalization of same sex marriage in the United States led to swift and substantial state-wide differences in implicit and explicit antigay bias (Ofosu, Chambers, Chen, & Hehman, Reference Ofosu, Chambers, Chen and Hehman2019). Likewise, Götz et al. (Reference Götz, Ebert, Gosling, Obschonka, Potter and Rentfrow2021) showed that changing amenities in cities (measured by housing prices) lead to swift and substantial changes in city-level openness.

To sum up, we readily acknowledge the importance of countries as salient and consequential containers of culture, and of households as the most nuclear cultural entity discussed by Uchiyama and colleagues. Nonetheless, we posit that to achieve a holistic and nuanced representation of the cultural environment and evolution against which genetic effects should be evaluated, it is imperative to consider the multiple geographic cultural layers impacting individuals and genetic heritability.