The present study compared 5‐ and 10‐year‐old North American and Israeli children's beliefs about the objectivity of different categories (n = 109). Children saw picture triads composed of two exemplars of the same category (e.g., two women) and an exemplar of a contrasting category (e.g., a man). Children were asked whether it would be acceptable or wrong for people in a different country to consider contrasting exemplars to be the same kind. It was found that children from both countries viewed gender as objectively correct and occupation as flexible. The findings regarding race and ethnicity differed in the two countries, revealing how an essentialist bias interacts with cultural input in directing children's conceptualization of social groups.