The title of this blog post is the Spanish equivalent of nature versus nurture. I recently attended a virtual presentation hosted by LAISPS (Los Angeles Institute and Society for Psychoanalytic Studies) that featured speakers discussing their perspectives on twin development. I feel that most professionals accept the mutual confluence of genetic and environmental factors in the formation of personality and psychological well-being. While I am interested in heritability statistics because they provide a generalized overview, my professional expertise focuses on the subjective experience of the patient. A psychotherapist develops a working knowledge of a twin patient by listening to her birth story, her parenting experiences, her sibling relationships, her school experiences, and her feelings about being raised as a twin. Simply having statistical evidence that twin studies demonstrate a strong genetic underpinning for social closeness does not specifically help my patient work through her issues of separation and individuation. On the contrary, if she acknowledges the study that shows that identical twin girls have the closest bond, how does she process the shame she feels because she is not close to her sister?

One participant at the presentation, who appeared resistant to the notion that twins do indeed suffer unique developmental challenges, pointed out that genetic data shows otherwise. He questioned, “Why do so many people search for their doppelgänger if being a twin can be fraught with difficulties?” An attendee responded that this search for one’s double may, in fact, stem from a universal, idealized fantasy of finding one’s lost twin. She went on to explain that the real experience of having a same-age sibling is intrapsychically and realistically complicated. Statistical data cannot fully explain a twin’s struggle to confront ambivalence, rivalry, identity confusion, and separateness. Many of the clinical cases that were presented focused on the long-term process required to help a twin patient develop a sense of self that was previously undefined.

I believe seminars such as this are vital to educating others about the psychology of twinship. Many clinicians are curious about the nuances of this special dyadic experience. I appreciated that one of the presenters made a clear distinction between psychopathology and patterns of development. Twins demonstrate distinctive adaptations to unique developmental criteria, and the general public should take this into account rather than pathologize same-age siblings’ behavior when it does not match stereotypic expectations.

Image courtesy of Stuart Heath (CC BY 2.0)