National Identity Is Not Purely Social: Heritable Links to RWA in a Norwegian Twin Sample
Social Identity Theory (SIT) assumes that group identification arises primarily through socialization and contextual dynamics. Yet few studies have tested whether such identifications share underlying biological architecture with core ideological traits. Using data from 2,097 Norwegian twins, we provide biometric evidence that national identity is not solely a socially constructed attitude, but reflects stable heritable dispositions aligned with specific ideological systems. Univariate ACE models showed that national identity is moderately heritable (h² ≈ 22%) with negligible shared environmental influence. Bivariate ACE models further revealed a strong genetic correlation between national identity and Right-Wing Authoritarianism (RWA; rA = .72), but a nonsignificant correlation with Social Dominance Orientation (SDO; rA = .18). This asymmetry suggests that national identity is genetically embedded within the RWA family of threat vigilance and norm-enforcement processes, rather than within hierarchy-oriented motivations captured by SDO. These findings challenge SIT’s implicit assumption that identitybased attitudes originate mainly from contextual and intergroup processes. Instead, they indicate that national identity is partly rooted in heritable dispositions that overlap with authoritarian motivational systems. This biologically grounded structure may help explain why certain identity-based attitudes persist across contexts and resist purely social explanations.