Researchers had kept them apart with different adoptive families to investigate theories over 'nature and nurture'.
Telling their amazing story for the first time, the twins, who were born in New York, said they might have remained oblivious if Elyse, who had been living in Paris, had not decided to look for her birth mother. She was told that the mother was not interested in meeting her, but was then informed she had an identical twin called Paula. Social workers eventually managed to reunite the pair.
After their emotional meeting, twin sisters discovered that, they had been part of research conducted by psychologists - thought to be the only study of its kind on twins separated from infancy.
This experiment was so secret that not even their adoptive parents were told the full truth. They were told only that the children were part of an ongoing study.
The twins tracked down and confronted the scientists behind the study, including Peter Neubauer, a child psychiatrist. They allege he showed no remorse and offered no apology.
A year after the study ended, in 1980, the State of New York issued guidelines stopping the separating of identical twins by adoption. Perhaps aware that his research would be criticised, Mr Neubauer reportedly locked the study in a university archive not to be opened until 2066. Link