Understandably, twin closeness and identity that starts to develop at conception in the mother's womb continues differently at birth and as twins mature. Because twins can be and are separated gradually, twins develop a sense that they are two people. Twin closeness often leads to over-identification. By this, I mean they psychologically believe that they are emotionally a part of their twin. Especially in early childhood, when one twin cries, the other twin also cries. I have observed the merger of twin personalities many times. Obviously, believing they are merged is an unconscious and conscious way of thinking that creates serious identity confusion between the twin pair. Parents and other close friends and family experience over-identification that grows and develops over time; this includes pressure from the twin pair’s internal and external worlds.

Normal twin identity confusion over “what belongs to which twin” and “who caused the present problem” are always subject to each twin's personal belief. More often than not, there is no agreement about who created the catastrophe. Almost any problem, from “who let the dog run wild in the street,” to “who ate our favorite cookies,” can be argued over and over again with amazing intensity. Over-identification creates twin fighting and confusion for those who are around. Twin confusion is hard for everyone involved. Unfortunately, it is not unusual for twins to misapprehend that they are over-identified with their twin.........

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