Twin Research for Everyone. From Biology to Health, Epigenetics, and Psychology

Table of Contents

Section 1. Background 1. History of Twin Studies John C. Loehlin 2. Prevalence of Twinning Worldwide Andr�s P�ri 3. Twin Family�Registries Worldwide Yoon-Mi Hur, Veronika V. Odintsova, Juan R. Ordonana, Karri Silventoinen, and Gonneke Willemsen

Section 2. Phenomenon of Twinning 4. Biology of Natural Twinning GARY David STEINMAN 5. Management and Outcome of Twin Pregnancies Gian Carlo Di Renzo, Valentina Tosto, Irene Giardina, Valentina Tsibizova 6. Conjoined Twins Julia Metneki and Peter Varjassy

Section 3. Twin Families 7. Growing up as Twins: The Perspective of Twin Researchers Adam Domonkos Tarnoki, David Laszlo Tarnoki, Julia Metneki and Nancy L.�Segal 8. Parenting of Twins, Triplets, or More Monica Rankin 9. Reared Apart Twins: Background, Research, Case Studies and What They Reveal About Human Development Nancy L.�Segal and Francisca J. Niculae 10. Opposite-sex Twins in Medical Research Lucas Calais Ferreira,�Sue Malta, and John L. Hopper

Section 4. Twin Methodologies 11. Establishing a resource for genetic, epidemiological and biomarker studies: the important role of twin registers Veronika Odintsova, Gonneke Willemsen, Conor V. Dolan, Jouke-Jan Hottenga, Nicholas G. Martin, P. Eline Slagboom, Juan R. Ordo�ana, Dorret I. Boomsma 12. Methodology of Twin Studies Jos� J. Morosoli, Brittany L. Mitchell, and Sarah Medland 13. Twin Studies of Complex Traits and Diseases Christopher R. Beam, Alice�J.�Kim, and Tinca J.C. Polderman 14. Use of Twin Studies to Make Inference About Causation for Measured Exposures by Examining Familial Confounding Vivienne F. C. Esser, Shuai Li, Minh Bui, and John L. Hopper 15. Twin Research in Clinical Trials Athula Sumathipala and Kaushalya Jayaweera

Section 5. Behavior 16. Twin Studies in Social Sciences EIena Cristina Mitrea and Levente Littvay 17. Childhood Development of Psychiatric Disorders and Related Traits Isabell Brikell, Paul Lichtenstein, and Henrik Larsson 18. Happiness and Well-being: The Value and Findings from Genetic Studies Margot P. can de Weijer, Lianne P. de Vries, and Meike Bartels 19. Twin Studies of Personality Juko Ando 20. Twin Research in Psychopathology Lisabeth Fisher DiLalla, Matthew R. Jamnik, Riley L. Marshall, Emily C. Pali, and David DiLalla 21. Cognitive Aging: The Role of Genes and Environments in Patterns of Change Deborah Finkel, Nancy L. Pedersen, and Chandra A. Reynolds 22. Twin Studies of Smoking and Tobacco Use Jaakko Kaprio

Section 6. Health 23. Anthropometric Twin Studies Karri Silventoinen 24. Twin studies of cardiorespiratory disease, daily cardiovascular activity and imaging Adam Domonkos Tarnoki, Gonneke Willemsen, Eco de Geus, and David Laszlo Tarnoki 25. Pediatric Twin Studies Catarina Almqvist and Paul Lichtenstein 26. Twin-Singleton Differences Kaare Christensen and Matt McGue 27. Twin Studies of Puberty and Behavior Holly T. Pham, Adriene M. Beltz, Robin Corley, and Sheri A. Berenbaum 28. Muscoloskeletal Twin Studies Paulo Ferreira and Munkh-Erdene Bayartai 29. Contributions of Twin Studies to Cancer Epidemiology Wendy Cozen, Esther Lam, Maryam Salehi, Victoria K. Cortessis, Tuong L. Nguyen, James Dowty, John L. Hopper, Shuai Li and Thomas M. Mack 30. Epigenetic Studies of Neurodevelopment in Twins Jeffrey Mark Craig, Namitha Mohandas, Yuk Jing Loke, Jennifer Eleanor Snowball, Yen Ting Wong and Garth Stephenson 31. Contributions of Twin Research to the study of Alzheimer's Disease and Related Dementias Matthew Sebastian Panizzan, Jeremy Elman and Eero Vuoksimaa

Section 7. Twin Research: Genetics, Epigenetics, Microbiome, and Environmental Adaptation 32. Twins and Omics: The Role of Twin Studies in Multi-Omics Fiona Alysa Hagenbeek, Jenny van Dongen, Rene Pool, and Dorret I. Boomsma 33. Epigenetics Aino Heikkinen, Sara Lundgren, and Miina Ollikainen 34. An Experiment in Co-Twin Control: Adaptation to Space Travel Carole Tafforin and Nancy Segal 35. Environmental Risk Factors for Neurodevelopmental Disorders: Evidence from Twin Studies Garth Stephenson and Jeffrey Mark Craig 36. Microbiome Studies and Twin Research Joohon Sung, Hang A. Park,�and Sooji Lee 37. Chromosomal Anomalies, Monogenetic Diseases, and Leukaemia in Twins Iren Haltrich and Anna Lengyel

Section 8. Conclusion Summary Adam Domonkos Tarnoki, David Laszlo Tarnoki, Jennifer Harris and Nancy Segal Appendix: Resources, Websites, Twin Organizations, and Further Reading Adam Domonkos Tarnoki, David Laszlo Tarnoki, Jennifer Harris and Nancy Segal

Authors

Adam D. Tarnoki Radiologist and Researcher, Department of Medical Imaging, Semmelweis University, Hungarian Twin Registry, Budapest, Hungary. Dr. Adam D. Tarnoki is an assistant professor, radiologist and twin researcher at Semmelweis University Medical Imaging Center and Department Head, Department of Radiology at National Institute of Oncology, Budapest, Hungary. He is a founding member of the Hungarian Twin Registry. He has presented more than 200 international lectures and has authored over 150 publications. He is a board member of the Hungarian Society of Radiologists and teaches radiology in English, German and Hungarian at Semmelweis University. Dr. Tarnoki serves as vice-president of the Hungarian Medical Association of America Hungary Chapter. He has also served as a member of the local organizing committee and Faculty of the 3rd World Congress on Twin Pregnancy and the 15th Congress of the International Society for Twin Studies (ISTS) in Budapest, Hungary, 2014 and the local host of the 19th International Congress on Twin Studies hold online in November, 2021. He serves as a deputy editor-in-chief of the Hungarian Radiology journal and he is the president of the International Society of Twin Studies (ISTS) since 2022. David L. Tarnoki Radiologist and Researcher, Department of Medical Imaging, Semmelweis University, Hungarian Twin Registry, Budapest, Hungary. Dr. David L. Tarnoki is an assistant professor, radiologist and twin researcher at the Semmelweis University Medical Imaging Center and Head of Oncologic Imaging Diagnostic Center, National Institute of Oncology, Budapest, Hungary. He is a founding member of the Hungarian Twin Registry and has presented more than 200 international lectures and authored over 150 publications. He is the board member of the Hungarian Society of Radiologists and teaches radiology in English, German and Hungarian at Semmelweis University. Dr. Tarnoki serves as secretary of the Hungarian Medical Association of America Hungary Chapter and is a member of the Academy of Young Researchers, Hungarian Academy of Sciences. He has also served as a member of the local organizing committee and Faculty of the 3rd World Congress on Twin Pregnancy and the 15th Congress of the International Society for Twin Studies (ISTS) in Budapest, Hungary, 2014 and the local host of the 19th International Congress on Twin Studies hold online in November, 2021. He is the secretary of the International Society of Twin Studies (ISTS) since 2022. Jennifer R. Harris Director of Research, Center for Fertility and Health, Norwegian Institute of Public Health, Oslo, Norway. Dr. Jennifer R. Harris is currently a Research Director at the Center of Fertility and Health at the Norwegian Institute of Public Health in Oslo, Norway. She has interdisciplinary training in life-span development and genetics. She has been conducting twin research throughout her academic career. She is the past president of the International Society for Twin Studies, a recipient of the James Shields Award for outstanding research in behavioral genetics, and is the scientific director of the Norwegian Twin Registry. Dr. Harris has broad commitment to the wider scientific community and serves on several expert panels, boards, steering groups, scientific advisory committees and editorial boards. Nancy L. Segal Psychology Professor of Psychology at California State University, Fullerton and Director of the Twin Studies Center, CA, USA. Dr. Nancy L. Segal is currently Professor of Psychology at California State University, Fullerton and Director of the Twin Studies Center. She has authored over 250 scientific articles and book chapters, as well as seven books on twins, most recently, Deliberately Divided: Inside the Controversial Study of Twins and Triplets Adopted Apart. Her 2012 book, Born Together-Reared Apart: The Landmark Minnesota twin Study, won the 2013 William James Award from the American Psychological Association. Dr. Segal has received several international awards, including the James Shields Award for Lifetime Contributions to Twin Research (International Society for Twin Studies) and the International Making a Difference Award (Multiple Births Canada). She is also the 2016 recipient of the prestigious Wang Family Excellence Award from California State University. Dr. Segal has contributed to national and international media, including the New York Times and the Washington Post. She has been a frequent guest on national and international television and radio programs, such as the Today Show, Good Morning America, the Martha Stewart Show, the Oprah Winfrey Show, The Forum (BBC) and the Hidden Brain National Public Radio).