Twins often feel the need to explain to singletons, that, "No, we are not exactly alike in every way. We do have our own interests, and no we don't think we look anything alike." It's as if twins must prove they are different from one another in order to establish themselves as individuals. Undoubtedly, there is a close connection between all twins. Given the intimate space twins share during fetal development, a physical and emotional bond often develops between twins once they are born. This bond remains throughout their lives, and remains a distinct symbol of their identity as a twin pair. However, it must not be forgotten that two individuals make up a twin pair, and that each twin emerges with her own identity, often quite different from her twin's.

The extent of differentiation that one should attain from her twin is a lifelong question with which a twin struggles. It has been said that diffentiation can be a means for avoiding direct competition with one another, which can be quite painful given the degree of similarity between twins. Differentiation of personality and self is governed by external as well as internal forces and two factors play key roles in the development of twin differentiation: the role of differential identification with each of the parents and the role of competition in the twinship.

Parental identification

Twins often divide the parents as primary objects of attatchment. Since twins are a lot of trouble to raise, parents sometimes divide the labor of raising them by singling out one's own twin to attend to, hence the identification with one over the other parent. Other times, each twin's personality and temperment plays a role. One twin's interests and personality match her father's, while the other twin and her mother feel more comfortable together. Differential identification seem to have clear implications in areas of activities, sexual preference, personality, parenting styles and learning styles. It is clear that major differences between some twins are consciously related to their different relationships with each of their parents. Siblings can also play a role. Sometimes an older sibling is assigned to each twin, and the effect of each twin's relationship with their older siblings can be profound.

Parents are often confused with which twin is which, and sometimes resort to color-coding their children's clothing, piercing their ears, or painting their toe-nails different colors when they are small and still difficult to tell apart. Later in life, twins admit the negative aspects of this coding system. "I'll always despise that shade of green,"said one color-coded twin. Once the opportunity comes to choose one's own clothing, twins express their newfound sense of freedom. "Sometimes we chose the same thing , sometimes not, but I got to wear what I wanted."

Competition between twins

Twins who are dressed alike or who were encouraged to do similar things feel the need to overaccentuate their differences in order to maintain a sense of themselves as separate individuals. Competition between twins starts early. The major source competition is for parental attention. Later in life, twins tend to develop separate interests to avoid competition, since competative situations create such undesirable boundaries between them. There is a flipside to this, however: "The differenciating elements which might serve to avoid competition may actually contribute increased competitive feelings, especially if those differentiating elements involve praise, acknowledgement, or other rewards." Clearly, the relationship between differentiation and competition is a circular and complex one. Schools have some influence on the mediating of differentiation and competition between twins as well.

Many schools have a separation policy for twins, and most families of twins support this policy. My own sister and I were separated after 2nd grade and were fine with it. Pro-separation arguments include the following: 1)If twins are put in the same classroom, their work and performance will be under constant comparison, thus encouraging jealousy and friction. 2) If look-alike twins are in the same class, it may be confusing and difficult for the teachers and classmates. Twins may exploit this opportunity and cheat or get into "various kinds of mischief." 3) Keeping twins together prevents them from making friends on their own, or broadening their horizons , and inhibits their freedom to become individuals and develop their own interests. The latter statement gives little credit to twins for their individual responses and ambitions, but in general, these policies do encourage twin differentiation and individuality.

Twin's subjective experience as individuals differ and these experiences shape them as individuals. Differentiation is an important issue for twins, and it is difficult to balance the desire to retain the unique twin bond, yet also define one's own identity as an individual. The degrees of similarity do vary among twin pairs, from twins who still dress and speak alike into old age, to twins who follow completely different paths in life. Differentiation in the twin situation can offer a "yardstick with which to assess the twin's so-called normality." Granted the twin relationship is a complex one, the more secure in their individual and shared identities, twins may develop close and long-lasting relationships with one another "which is not based on excessive dependance and a loss of self-object boundaries."