In her interview on TED Radio Hour, couples therapist and author Esther Perel discusses her philosophies on love and marital relationships. She dismisses the popular claim that a spouse could be one’s best friend. She explains, “Many people treat their partners in ways they would never treat their best friends. And [they] allow themselves to say and do things that no best friend would ever accept. Friendship does not operate along the same lines [as marriage].”

That statement made me wonder about the twins I’ve interviewed. Are their relationships more similar to a marriage, where they are uninhibited in their communications and actions? Or are their relationships more akin to best friends where there is a genuine attachment, but there is also a limit to what they can say and do?

Twin Yearning

Researchers have noted that twins tend to project their twinship onto other significant relationships (also known as “twin yearning”). For twins who are so close that they only know what it is like to feel attached to another person and to feel part of a set, they typically seek a life partner who can essentially comprise the other half of their identity.

Twins: “Quasi-Marriages”

Among the twins I interviewed, many described their relationships as quasi-marriages — at least as applied to the first eighteen years of their lives. During that time, they collectively made decisions, nurtured a partnership, fought, made up, traveled together, etc. They essentially did everything married couples do save for the physical, romantic, and sexual acts of intimacy.

Twin interviewees told me that they were disappointed to learn in adulthood that other people typically do not deliver the unconditional love and mutual understanding to which they had grown accustomed with their respective twin siblings.

“Love outside of the twinship doesn’t work that way,” commented one interviewee. “I remember feeling surprised that I had to make personality or behavioral changes in order to make the relationship with my boyfriend work. I mean, in my relationship with my [twin] sister, I was allowed to be myself.”

Another twin interviewee concurred: “With [my twin sibling], I don’t have to work so hard to be understood.”

Conclusion?

Look at the other relationships in twins’ lives: parents are there in the beginning, but they leave early. Spouses are there until the end, but they arrive late. One’s twin sibling, however, is with her the entire time — from the beginning until the end.

So maybe a close twin relationship mimics neither a best friendship nor a marital partnership. It resides in its own category. It encompasses unconditional love, a long history of shared experiences, freedom to be oneself, and deep, deep knowledge and understanding of the other person.

It is an intimacy like no other.