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Twins and the Balance of Power: The Weight of Developmental Differences


Dominance dynamics in twins are complex and influenced by multiple factors, including development, zygosity, and personality. The study highlighted that in mixed dyads, the typically developing twin tends to assume a dominant role, and this difference can have implications for the emotional well-being of both.


Twins share a prenatal environment, a birth date, and a life trajectory that unfolds in parallel, from infancy to adulthood.


However, while they share these milestones, twins are distinct individuals, forming a unique relationship that blends similarities and differences.


This bond is marked by specific dynamics, including aspects of relative power, where one twin may assume a more dominant role, while the other adopts a more submissive role.


As in other types of relationships, interactions between twins involve issues such as leadership and submission, influenced by factors such as birth order, development, and personality.


In single-sibling relationships, birth order often determines dominance: older siblings tend to lead and set rules, while younger siblings often follow, imitate, or submit.


However, this logic does not directly apply to twins, who share the same age. This raises the question: What factors influence dominance in twin relationships?

Early research has shown that dominance dynamics between twins are generally more symmetrical than between singletons. In a retrospective study of adult twins, dominance was found to vary by domain: psychological, verbal, or physical.


Furthermore, the twin who is more dominant in one of these domains tends to be more balanced or even submissive in others, suggesting that neither twin is completely dominant in the relationship.


Another important finding is that dominance dynamics between twins change over time, becoming more balanced as they mature.


However, persistent asymmetries may be associated with mental health challenges, such as depressive symptoms in submissive twins and anxiety in dominant twins. These findings indicate that the balance of power between twins can have significant implications for the emotional well-being of both.


When one twin is typically developing (TD) and the other is atypically developing (non-TD), dominance dynamics may become more asymmetrical. Twin pregnancies have a higher risk of complications, which can lead to developmental delays in one or both twins.


Research suggests that atypically developing twins often occupy a more submissive role than their typically developing sibling, regardless of birth order. This difference may be exacerbated by constant comparisons between twins, who share the same age and developmental background.

Studies also suggest that, unlike singletons, twins with atypical development have fewer opportunities to assume a dominant role in their relationship. This can make it more difficult to balance power within the pair, even if the developmental delay is outgrown later in childhood.


Each twin’s personality also plays a crucial role in dominance dynamics. Some children are more likely to control or lead, while others may be more likely to follow. In addition, zygosity (whether the twins are monozygotic, MZ, or dizygotic, DZ) influences these dynamics.


Monozygotic twins, who share nearly 100% of their genes, tend to be more similar in behavior and personality, resulting in more symmetrical relationships.


In contrast, dizygotic twins, who share an average of 50% of their genetics, often exhibit greater variation in their behaviors, which can lead to more asymmetrical relationships.


The current study, conducted by researchers at The Academic College of Tel-Aviv Jaffa, Israel, investigated how atypical development affects dominance dynamics between twins.


They analyzed monozygotic and dizygotic twin dyads, including cases in which one twin was non-typically developing. In addition, the study explored how these dynamics change over time, particularly when developmental delay is overcome.


The data came from an Israeli longitudinal study of 1,657 families of twins born in 2004–2005.


Mothers reported on their children’s developmental status at four time points: at 3, 5, 6.5, and 8–9 years of age. Questionnaires assessed the twins’ relationships, including aspects of dominance. A subsample of fathers also completed the questionnaires.


The study focused on two types of dyads:


  1. Dyads with similar developmental conditions: both twins with typical development or both with atypical development.


  2. Mixed dyads: one twin with typical development and the other with atypical development.


The results revealed that in dyads with similar developmental conditions, there were no significant differences in dominance, regardless of whether both twins had typical or atypical development.


In contrast, in mixed dyads, the typically developing twin was consistently more dominant. This asymmetry persisted throughout childhood, even when the atypically developing twin outgrew the developmental delays.

Furthermore, monozygotic twins showed more symmetrical dominance relationships than dizygotic twins, regardless of developmental status. This suggests that genetic similarity may mitigate power asymmetry between twins.


Dominance dynamics in twins are complex and influenced by multiple factors, including development, zygosity, and personality.


The study highlighted that in mixed-sex dyads, the typically developing twin tends to assume a dominant role, and this difference may have implications for the emotional well-being of both.


However, demonstrating dominance behaviors may be possible for the atypically developing twin in other contexts. These findings are important for parents and caregivers, who can use this information to adjust their parenting strategies and promote more balanced interactions between twins.


Understanding and supporting each child’s emotional and social needs can help minimize the impacts of power imbalances and promote the well-being of twins as individuals and as a unit.



READ MORE:


“You and me”: Parental perceptions on asymmetry in twins' development and their dominance relationship dynamics

Hila Segal, Yonat Rum, Adi Barkan, Ariel Knafo-Noam

Family Relations. First published: 26 October 2024 


Abstract:


This study investigated the role of nontypical development in the relative dominance in twins' relationships throughout childhood. Dominance dynamics, affecting siblings' well-being, are different in twins than in singletons for whom age and development often dictate sibling hierarchy. These dynamics in twins, who share similar ages and developmental contexts, remain underexplored and demand further understanding.

A longitudinal study surveyed 1,547 mothers and 536 fathers of 322 monozygotic (sharing nearly 100% genes) and 1,199 dizygotic (sharing 50% genetic variance) twin pairs, aged 3 to 8–9. Both parents reported on the twins' relationships. Mothers reported whether either twin had a developmental condition. No dominance difference was found in similar developmental conditions dyads, whether both twins had typical or nontypical development. However, in dyads where twins differed in the developmental condition, nontypically developing twins were less dominant than their typically developing cotwins. This dominance imbalance persisted throughout childhood, even if initial developmental issues were resolved. From parents' perspectives, nontypical development does not, in itself, prevent children from demonstrating dominance behaviors in twinship, but it is more likely that the asymmetry in developmental conditions is associated with the relationship between the twins. According to parents' perceptions, twins with nontypical development might experience imbalances in their relationship throughout childhood when their co-twin is a typically developing child. However, demonstrating dominance might be possible for them in other contexts. Understanding these dominance dynamics is vital for caregivers, informing tailored parenting strategies and interventions to support the well-being of children.

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