Predictable Growth-Focused Changes in Twin Relationships
The contributions of life stages to changes in relationships between twins.
Posted October 13, 2025 | Reviewed by Michelle Quirk
In very early life, twins are very close and gradually learn to tolerate being separate from one another. Their first separation at birth and in their early months of life should be carefully monitored, as their sense of self is intertwined with their co-twin, sharing their mother’s womb, and sharing many days together since birth. People question whether infant twins are one.
My answer is: “No, no, they are two individuals physically. Emotionally, they are connected in many ways and may appear to be one. When one twin cries, the other twin may cry. Often it can seem that infant twins react as if they are one.”
Only gradually, with physical experiences apart from each other, do twins develop a sense of individuality. Because they cannot explain themselves as infants or even as toddlers, we cannot know when twins realize that they are two different people. My best guess is that hitting the other twin, pulling their hair, or biting helps the twin understand that they are not attached; the co-twin is an eerily similar but different human being. The twin relationship begins and grows as they play and sleep together, share food and toys, and strive for parental attention .
Watching the twin relationship evolve and become a viable way to gain comfort from each other is heart-warming and amazing for parents and other interested observers. Physical separation is a profound struggle because remarkable closeness developed in the womb. Being apart can create fearful behavior for twins at most stages of life. Separation anxiety takes a very long time to get over. When parents manage separation thoughtfully, giving separation experiences that twins can tolerate easily, the fear of being apart is less threatening.
By the age of 2, enough maturity has developed for twins to be on their own without their co-twin for short periods of time. The development process has contributed to a more established sense of individuality for twins. Having more time alone has a remarkable growing effect on identity development and on twin issues such as fighting and sharing. Anger at each other develops and expands. Neediness for attention from caregivers is more apparent and often exploited for obvious gain.
Controlling twin unhappiness from being separated can be managed with close attention to what they are able to tolerate. Too much stress from separation is not at all helpful because it creates painful anxiety. But ignoring a twin’s early need for separation can limit the development of learning life skills, because dependency develops instead. To reiterate, separation anxiety can be reduced when it is considered an important priority and your best analysis is used.
Talking in Simple Sentences
The next growth spurt related to age 4 or 5 occurs when twins can talk in simple sentences to their co-twin and to their caregivers. While the ability to use one- or two-word sentences starts earlier, more advanced language use contributes profoundly to more and more communication with the co-twin and their family. This growing ability allows twins to share details of their thoughts and feelings, ideas, and needs. As talking becomes more expansive, a better understanding of a twin’s life develops. A twin better understands their life, in other words.
Expressing What Twins Want to Eat, Where They Want to Go, and What They Want to Do
While this growth spurt can easily be seen without words, actual verbal expression is more direct and effective. Expressing their needs out loud in words promotes inter-twin understanding and a better ability to comfort one another. Arguing, fighting, and sharing feelings, thoughts, and interests make twin bonding more established and reliable.
Adolescence Clarifies Identity Development and Directs Twins to Explore Cognitive and Sexual Choices
The teenage years provoke dramatic changes in identity and in the bond twins share. Thoughts about academic interests and careers come into play, as well as opposite- sex or same-sex choices. College and working become a focus. Anger at one another is more visible and contentious. Fighting can lead to estrangement if communication skills are underdeveloped. Sharing friends is often difficult, problematic, and should be avoided, especially as teenagers .
Adulthood: A Final Chance to Resolve Estrangement Issues
This age-related change in the twin relationship is most dramatic and stressful as loyalty and betrayal come into the bond that twins share, and can be confusing and very hurtful. While dealing with the teenage years for twins can be a struggle, adulthood is very crucial and must be contended with as much as possible. Making up with your twin is a possibility at this stage of life.
A remarkable change in the twin relationship emerges in the senior years, and it is often similar to the early relationship that twins shared. Dependence on one another can be quite important and necessary if one twin needs physical, mental, or financial help. Older adults often resolve their issues because of how much they care for each other. Sometimes anger is so deep that estrangement takes hold and cannot be easily resolved.
Twin loss is frightening and must be attended to carefully to avoid the lasting aftereffect of not being able to move on without your twin. In other words, it is common for twins to hold onto the loss of their twin and not try to, or avoid, making new friends and interests because of their grief . Essentially, a twin has to adjust to twin loss to further survive in the world.
Conclusions: Once a Twin, Always a Twin
While many people want to be twins and have to live with this disappointment, others who are twins find twinship very crippling. I have talked with twins who actually do not want to be twins because of identity confusion from others and constant questions about how they compare to their twin. I admit that questions from “onlookers” are very tiring and sometimes embarrassing. I think that being a twin is hard and confusing, and not the ideal situation that many people tend to believe it is. Careful attention to how to raise twins needs to be pursued if twins are to learn not to compete with each other.
I have learned from talking with many twins that knowing they don’t “have to” get along is a deep-seated relief. Anger that twins have is also combined with deep love. Anger toward each other lives side by side with pride in their twin and a longing to be with them that never really goes away.
www.estrangedtwins.com
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Barbara Klein, Ph.D., Ed.D. , is an author and educational consultant who has done extensive research on the development of twin identity.
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This article is part of the Bringwise Psychology Journal — daily insights on human behavior, mental health, and personal growth.