Twins share many things, like their prenatal environment, birth date, and the timeline of their lives from childhood to adulthood. However, they are also unique individuals with their personalities, even though they are in a close relationship with each other.
Like in any other relationship, there can be power differences between twins. One twin might be more dominant, while the other may be more passive.
A new study by researchers from the Hebrew University of Jerusalem and The Academic College of Tel-Aviv–Jaffa examines how differences in development can affect the balance of dominance between twins during childhood. The study mainly explored how differences in developmental conditions between twins, particularly when one child has a developmental condition and the other, do not affect their dominance dynamics over time.
The research surveyed over 1,500 parents of monozygotic and dizygotic twins aged 3 to 9. It found that when one twin was developing typically, and the other had a developmental condition, parents often saw the typically developing twin as the dominant one.
This dominance difference remained steady throughout childhood, even if the developmental issues of the twin with the condition were resolved. In cases where both twins had the same developmental condition, whether typical or not, there were no significant differences in dominance. The study suggests that it’s not the developmental condition itself but the difference in abilities between the twins that leads to dominance imbalances.
Parental perceptions played a significant role in shaping dominance between twins. Parents often focus on the differences between their twins, which can exaggerate how different they seem. This “contrast effect” can strengthen the dominance roles, influencing how twins interact and forming long-term relationship patterns. This fits with family systems theory, which says that family members’ roles affect each other.
The study also found that genetic similarity matters. Monozygotic (identical) twins, who share nearly the same genes, tended to have more balanced dominance roles than dizygotic (fraternal) twins, even when one twin had a developmental condition. This suggests that genes and personality traits play a part in shaping how dominance works in twin relationships.
Moreover, once dominance roles are set early in life, they stay the same, even if the developmental issues improve. This is explained by role theory, which says that family roles become fixed over time. To prevent these roles from becoming too ingrained, parents can help by encouraging their twins to form separate identities, interact with others outside the family, and give the less dominant twin chances to take charge in different areas.
This research highlights how developmental differences shape twin relationships and the importance of parental awareness in creating balanced relationships. Parents can help their twins develop healthier social and emotional skills by addressing these issues early.
Journal Reference:
- Hila Segal, Yonat Rum, Adi Barkan and Ariel Knafo-Noam. “You and me”: Parental perceptions on asymmetry in twins’ development and their dominance relationship dynamics. Family Relations. DOI: 10.1111/fare.13104
