Genetic anthropology studies offer evolutionary and migratory narratives to characterize individuals and human groups based on genetic traits. From the analysis of genetic information, these studies construct genealogies that connect body characteristics with geographies and stories of origin. In recent years, an international group of researchers worked in a project focused on Latin American populations. In this paper, we present the results of our ethnographic work and interviews with participants in this project. Based on this material, we show that Mexican participants tend to use their physical appearance, typological ideas of human difference, family stories and family names to give meaning to scientific terms such as genetic ancestry. Participants rely on shared visual habits to interpret their own and others' appearance and to negotiate their belonging to racial, ethnic and family groups.