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A groundbreaking study led by researchers from the Hebrew University of Jerusalem and The Academic College of Tel-Aviv–Jaffa has uncovered new insights into the influence of developmental differences on sibling dominance dynamics in twins. The research, published in Family Relations, suggests that twins where one child is typically developing and the other has a developmental condition often display a persistent dominance imbalance—where the typically developing twin assumes the dominant role, even after developmental gaps are closed.
The study, conducted by Prof. Ariel Knafo-Noam, Dr. Yonat Rum, Dr. Hila Segal, and Adi Barkan, surveyed over 1,500 parents of monozygotic (identical) and dizygotic (fraternal) twins, aged 3 to 9, exploring the relationships between twins with varying developmental conditions. The researchers found that the perceived dominance of the typically developing twin over their nontypically developing sibling remained stable throughout childhood, regardless of whether the developmental differences were eventually resolved.
The study highlights the significant role of parental perceptions in reinforcing these dynamics. Parents often exaggerate the differences between their twins, a phenomenon known as the “contrast effect,” which can inadvertently cement the dominance roles within the sibling relationship. This bias can influence how twins relate to one another, contributing to long-term relational patterns that can shape their social and emotional development.
Interestingly, the study also found that genetic factors influenced these dynamics. Monozygotic twins, who share nearly identical genetic material, were more likely to show balanced dominance relationships compared to dizygotic twins, even when there were developmental differences. This suggests that genetic similarity and personality traits may play a role in fostering more equitable sibling relationships.
The findings underscore the importance of understanding the delicate balance of twin relationships and the need for parents to be mindful of their perceptions and behaviors. The persistence of dominance roles in twins, once established, can be explained through role theory, where early patterns of behavior, reinforced by parental input, become ingrained over time.
To support both children’s growth, the researchers recommend that parents create opportunities for more balanced dynamics. This could include fostering individuality, encouraging external relationships beyond the twin bond, and providing avenues for the less dominant twin to assert themselves in specific areas. By addressing these patterns early, families can help reduce the long-term impact of dominance roles on the emotional well-being of both children.
This study offers valuable insights into the complexities of twin relationships and highlights the importance of fostering equality to promote healthy development for both siblings.
More Information:
Segal, H., et al. “You and Me: Parental Perceptions on Asymmetry in Twins’ Development and Their Dominance Relationship Dynamics,” Family Relations (2024). DOI: 10.1111/fare.13104.
