|Twin sisters posing at the annual double take parade in 2007, in Twinsburg, Ohio - the largest annual gathering of twins in the world. (Photo by Rick Gershon/Getty Images).|
Sirpa Pietilä and her team interviewed most of the participants in their homes, although a few opted to meet in a public place. The participants were aged 78 to 90, including seven intact pairs of twins (where both were still alive) - four identical pairs and three non-identical or "fraternal". There were also six twins who'd lost their twin sibling - two of these participants were identical, four fraternal.
In terms of companionship, the participants made the kind of comments that we're used to hearing about twins. Losing a twin was devastating. "I'm only half now, there's only half of me left," said Norah (identical), aged 90. In childhood it felt entirely normal to be a twin, and the twins described how they expected other children to also come in twos.
Yet, the surprising message to come from the interviews was the way these twins had clearly strived through life to forge a strong sense of self (presumably unlike those attending Twinsburg - see pic above). The participants drew attention to the differences in their birth order (one twin is always slightly older than the other by a few minutes), with the elder usually seen as more dominant. They emphasised their deliberate pursuit of different hobbies and careers. Indeed, none of the participants had worked in the same company as their twin. The interviewees also tended to describe a closer affiliation with a different parent than their twin. They also described resenting being referred to as "the twins" - as a single social unit rather than as two different people. As soon as they were old enough, the participants said they'd chosen to wear different clothes from their twin.
"It is symptomatic of the lifelong lack of confirmed individuality that these older twins of around 80 years of age still seemed to feel the need for emphasising that they were individuals," the researchers said.
Even the frustration of receiving identical presents persisted into old age. "… like recently it was our 78th birthday we both received vases … and my sister got exactly the same vase," said one female twin with disappointment. "And then from another grandchild we both received a large teacup each, my sister got one too, the same, but I didn't want to say anything. I can't understand how they don't think?"
Sirpa Pietilä and her colleagues acknowledged the limitations of their qualitative methodology - "objective truths cannot be obtained," they said, and there are obvious problems with relying on reminiscences. Nonetheless, they said their research broke new ground because most research of this kind has been focused on twins who are young. "It seems like there is an ongoing lifelong identity work of claiming oneself as an individual," the researchers concluded. This revelation can hopefully "lead to a greater sensibility towards the two individuals who make up a set of twins."
Pietilä S, Björklund A, and Bülow P (2013). 'We are not as alike, as you think' sense of individuality within the co-twin relationship along the life course. Journal of aging studies, 27 (4), 339-46 PMID: 24300054
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Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.