Group loyalty ensures that individuals favor their in-group over out-groups and is important for the continued existence of groups. As of yet, it is an unanswered question how children develop social group identifications and attitudes. Here, we investigate whether and how parental cultural values, as assessed via the GLOBE questionnaire relate to children’s manifestation of group loyalty. Overall, 78 5-year-old children from intercultural families administered a loyalty task. Results show that one important aspect for the formation and maintenance of groups, Ingroup Collectivism, was reliably related to children’s loyalty. The findings suggest that children’s attitudes of group loyalty are socially transmitted by the environmental cultural niche that parents set.