The 54-year-old identical sisters, Ellen Carbone and Melanie Mertzel, who have told their story for the first time to 60 Minutes reporter Liam Bartlett, say they deserve to see the "secret" data that was collected about them individually as children as part of the study by New York psychiatrist Dr Peter Neubauer, who died in 2008.
All videos, tests and records from the study are sealed at Yale University until 2066.
"It's my life. You shouldn't hide my life from me," Ms Carbone told Bartlett.
"I think any twin, I mean any person adopted, even if they weren't a twin or [in] a study would want to know what was said and tested and how they reacted to anything," Ms Mertzel said.
Ellen and Melanie were born in May 1966. The Louise Wise Adoption Agency in New York, which specialised in adopting out Jewish babies, separated the infant girls and placed them with families.
But neither their biological mother nor the families who adopted them had any idea they were guinea pigs in a secret experiment.
In total, four pairs of identical twins and one set of triplets were split up and sent to different homes as part of the study.
For Melanie and Ellen, it resulted in a deep sense of longing for something unknown throughout the formative years of their lives.
"I thought it was normal. I thought everybody wanted a twin sister … I was so jealous of [twins] and didn't understand why," Ms Mertzel told 60 Minutes.
"I always wanted a sister and here, I had a sister, like instantly. And not only just a sister but an identical twin," Ms Carbone said.
When they were 23, Ellen and Melanie discovered they were twins and found each other by chance when one of Ellen's aunts saw Melanie working at her parents' restaurant.
But their happiness in discovering each other turned to anger when it was revealed they had been deliberately separated as part of Dr Neubauer's grotesque experiment.
"We were identical and he robbed us of our childhood, robbed us of our closeness. He took away something from us that we will never, ever experience or have in our entire lives," Ms Carbone said.
"We describe him as a Nazi, honestly," Ms Mertzel said.
"I think that he was trying to play God and try to see if it was genetics or if it was how you're raised, your environment, what moulds you to be the person you are," Ms Carbone said.
Making matter worse, no scientific paper was ever published by Dr Neubauer about his study, leaving the twins wondering what their trauma was worth.
A twin expert, Professor Nancy Segal, says the psychological damage done by separating twins at birth is devastating.
"These individuals were deprived of what could have been the closest of human social relationships," Professor Segal told 60 Minutes.
"It really does seem that the twin's suffering and the suffering of their parents and their siblings and everyone who knows them, was really for nothing. There is no real end product here, nothing that we can say that we've learned."
Now Ellen and Melanie – and the other separated identical twins who were the unwitting subjects of the Neubauer study – are fighting to access the records of their own early lives, so cruelly manipulated by Dr Neubauer and his experiment.
"I don't think anyone could ever, ever, ever, ever apologise. And I don't think I could ever accept an apology. It's too late. You did it. It's done. You can't go back," Ms Mertzel said.
"You know the song, 'Is it too late now to say, sorry'? In this situation, absolutely."
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