Vol. 72 No. 2 (2024): NAMES: A Journal of Onomastics

What's in a Name: An Exploratory Study of Similarities and Differences Between Twins and Single-born Siblings

Emma Otta
Universidade de São Paulo
Eloísa de Souza Fernandes
Instituto de Psicologia da Universidade de São Paulo
Renata Defelipe
Instituto de Psicologia da Universidade de São Paulo
Keven Leandro dos Santos
Instituto de Psicologia da Universidade de São Paulo
Vinicius Frayze David
Instituto de Psicologia da Universidade de São Paulo
Nancy L. Segal
California State University, Fullerton

Published 2024-06-06


  • first name,
  • naming,
  • twins,
  • single-born siblings,
  • anthroponyms,
  • Brazil
  • ...More


The current paper investigates the intra-pair similarity of twins’ first names in comparison to non-twin siblings. The dataset was composed of 2,387 pairs of Brazilian names of same-sex individuals as a function of sex, age (< 18 years vs > 18 years), and self-reported zygosity (MZ: Monozygotic vs DZ: Dizygotic). We assigned scores to each pair of names according to a classification system of 12 categories of intra-pair similarity (0 = absent; and 1 = present). The final score was the sum of the points obtained. ANOVA revealed that MZ twins (95% CI 2.28-2.50) had more similar names than DZ twins (95% CI 2.03-2.26), who, in turn, had more similar names than non-twins (95% CI 1.45-1.87). Females (95% CI 2.38-2.57) generally had more similar names than males (95% CI 1.63-1.83), and siblings over 18 years of age (95% CI 2.34-2.56) were given more similar names than siblings under 18 years of age (95% CI 1.85-2.03). Our results support and extend previous findings providing insight into parental expectations about individuality-relationality that may influence the negotiation of relationship and construction of identity. By naming their twin children, parents emphasize twinness through similar names, whereas they emphasize the individuality of their single-born children through different names.


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