Determination of Twin Zygosity in Brazil: A DNA Validation of Two Short Questionnaires

Authors

DOI:

https://doi.org/10.22491/1678-4669.20230001

Keywords:

monozygotic twin, dizygotic twins, zygosity, questionnaire validation

Abstract

Twin research in Brazil is expanding and should be built upon solid foundations using zygosity questionnaires validated through DNA. Our goals were to adapt and validate two short zygosity questionnaires to Brazilian Portuguese using DNA testing in Brazilian twins. One hundred same-sex twin pairs (27 males and 73 females; M age = 30.92, SD = 12.87) answered socio-demographic and two short zygosity questionnaires. Blood samples were collected for DNA extraction, followed by a forensic analysis on 22 autosomic short tandem repeat plus amelogenin and DYS391 markers to obtain an individual genetic profile. According to DNA tests, 17% of twin pairs were classified as dizygotic and 83% as monozygotic. Both questionnaires correctly distinguished the zygosity with 96.7% accuracy, with a high Kappa index, comparable with each original validation. These DNA validated zygosity questionnaires may foster twin research in Brazil with stronger methodology.

Author Biographies

Marco Varella, Universidade de São Paulo

A biologist with master and Ph.D. in Experimental Psychology (Institute of Psychology - IP, Universidade de São Paulo - USP). He has a Postdoctorade in Behavioral Genetics and is currently a Post-doctoral fellow researcher in Evolutionary Psychology (IP-USP). His main research interests concern zygosity/twinning rates, misunderstandings and teaching human evolution, psychological underpinnings of anthropomorphism, mate choice/preferences, sexual strategies, intra/intersexual differences, vocational interests and career-choice, paleoarts aesthetics, evolution of musical/artistic propensities and motivations, and leadership and noncompliance during COVID-19 pandemics.

Eloísa Fernandes, Universidade de São Paulo

A psychologist and student of master degree at the Department of Experimental Psychology, Institute of Psychology, Universidade de São Paulo, Brazil. Her main research interests concern the study of subjective well-being, personality and individual differences, emotions, psychological processes and relationships in twins and siblings.

 

Cintia Fridman, Universidade de São Paulo

Associate professor at Department of Legal Medicine at Medical School in Universidade de São Paulo. Her expertise area is Human Genetics with main research interests focusing in Forensic Human Identification using molecular biology approaches.

Tania Lucci, Universidade de São Paulo

A psychologist with a master's and doctorate developed at the Department of Experimental Psychology, at the Institute of Psychology in Universidade de São Paulo, Brazil. Her main research interests concern the study of child development, attachment, emotions, family interactions and more recently psychological process of twins and their relationships.

Renata Defelipe, Universidade de São Paulo

A biologist with a Ph.D. in Experimental Psychology (Institute of Psychology, Universidade de São Paulo). Her research interests focus on human mental health, caregiver-infant relationships, social learning, and child development.

Lucas Fernandes, Universidade de São Paulo

A biologist with a master's degree at the Department of Experimental Psychology, at the Institute of Psychology in Universidade de São Paulo, Brazil. His main research interests concern the study of basic emotions, disgust, morality and sexuality.

Ana Laura Garcia, Universidade de São Paulo

A Biomedical Scientist with experience in blood analysis and Molecular Biology at the Laboratory of Immuno-Hematology and Forensic Hematology in Universidade de São Paulo – FMUSP.

Laís Antonio, Universidade de São Paulo

A Master's Degree student at University of São Paulo – USP, Forensic Sciences specialist by the Paulista Institute of Bioethical and Legal Studies - IPEBJ (2016) and Biological Sciences graduate at University of Franca - UNIFRAN (2010). Member of the Forensic Expertise Commission of OAB/SP. Reviewer of the Scientific Journal Brazilian Journal of Forensic Sciences, Medical Law and Bioethics. Judicial expert and technical assistant currently working with molecular biology / genetics (DNA) with training in blood collection and venipuncture by the Cruz Vermelha Brasileira (2018).

Nancy Segal, California State University

Professor of Psychology at California State University, Fullerton and Director of the Twin Studies Center. She has authored over 250 articles and six books on twins and twin development. Her 2012 book, Born Together-Reared Apart: The Landmark Minnesota Twin Study, won the 2013 William James Book Award from the American Psychological Association. Her other books include Twin Mythconceptions: False Beliefs, Fables and Facts About Twins (2017), Someone Else’s Twin: The True Story of Babies Switched at Birth (2011), Indivisible by Two: Lives of Extraordinary Twins (2007) and Entwined Lives: Twins and What They Tell Us About Human Behavior (2000). Her most recent book, Accidental Brothers (April 2018) follows the life histories of identical Colombian twins who were inadvertently exchanged at birth. Her work has been featured in the New York Times and the Wall Street Journal. Dr. Segal’s newest book, Deliberately Divided: Inside the Controversial Study of Twins and Triplets Adopted Apart, will be released in spring 2021. 

Emma Otta, Universidade de São Paulo

Full professor at the Department of Experimental Psychology, at the Institute of Psychology in Universidade de São Paulo, Brazil. Her main research interests concern the study of twins on psychological processes and behavior, subjective well-being and personality, twin relationship as an attachment bond, cooperation and competition, and the development and cross-cultural adaptation of psychological questionnaires. The University of São Paulo (USP) Twin Panel (Painel USP de Gêmeos) was formally founded in 2017 at the Institute of Psychology of the USP by a faculty team under her leadership.

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Published

2024-11-12

How to Cite

Varella, M., Fernandes, E., Fridman, C., Lucci, T., Defelipe, R., Fernandes, L., … Otta, E. (2024). Determination of Twin Zygosity in Brazil: A DNA Validation of Two Short Questionnaires. Estudos De Psicologia (Natal), 28(1), 1–12. https://doi.org/10.22491/1678-4669.20230001

Issue

Vol. 28 No. 1 (2023)

Section

Psychobiology and Cognitive Psychology

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