SEEING DOUBLE

What does it feel like to find out in later life that you are a twin? Three sets of sisters tell their stories of meeting for the first time - and what happened next

- Isabelle Aron

Imagine finding out late in life that there's someone out there who looks just like you: same eyes, same nose, same mouth. Not a doppelganger, but a twin you never knew existed. Discovering that you're a twin is "a life-changing experience", says Nancy L. Segal, a professor of psychology and the director of the Twin Studies Center at California State University, Fullerton.

Dr Segal has written nine books on twins and is now working on her 10th. Over the years, she has come across at least 100 pairs of reared-apart twins. In most cases the twins were separated at birth and adopted by different families. "Adoptees often feel that something's missing in their lives," Segal says. "I think it relates to the fact they don't look like their family members. They don't feel a certain kind of belonging, even though they're loved. When they find a twin, they can see themselves in somebody else. And that's important."

Through her research, Segal has found that twins are often similar even if they've grown up apart. "In personality, identical twins raised apart are as similar as identical twins raised together." This suggests we're similar to the people we live with because of the genes we share, rather than the environment. Segal has also found that identical reared-apart twins often feel closer than fraternal (non-identical) reared-apart twins. "What I've found even more striking is that when I've compared the twins' current closeness both identical and fraternal-to the adopted siblings they were raised with, they felt much closer with the twin. I've been surprised at how well they got along so quickly. It seemed as if they'd known each other all their lives."

Here, people who've found their twin later in life share what it's like to discover this missing part of themselves.

Sam Futerman and Anaïs Bordier, 36