They have now revealed their horror stories in a new television documentary made by the journalist who wrote the Philomena story.
Martin Sixsmith has interviewed many of the thousands of children taken from their mothers by the Catholic Church and handed over to American families.
The Irish Examiner reports that an estimated 2,000 illegitimate children were sent abroad by the church in what is described as the ‘adoption trade.’
The BBC Two documentary – Ireland’s Lost Babies – features Sixsmith investigating what happened to Irish children adopted across the US.
He has discovered that many of the parents were not properly vetted by the Church.
Some of the children were sexually and physically abused by their adoptive parents according to Sixsmith.
He told the Irish Examiner: “The more you talk to the children who were sent out to America – and there were hundreds of them – the more you realize what a lottery the whole system was.
“Some of the children had happy lives with the families they were sent to but many of them didn’t. Some of them were physically and sexually abused.”
One adopted child, now 62, spoke of how she was abused by her adoptive father not long after arriving in America as a small child in the early 1950s.
Mary Monaghan also revealed that her father had not been properly vetted by the Catholic Welfare Bureau.
She later discovered a document which showed only her adoptive mother was interviewed by the organization.
Monaghan was handed over to William O’Brien in Ireland by the nuns to be transported to America where her family life in California turned into a nightmare.
She revealed: “I would be ill and I had all kinds of allergies and would break out because I was allergic to food.
“My memories are terrible. I was physically punished for not being able to eat and if I did anything like wet the bed, like a little child does, I would be put in the toilet. The sexual abuse began very soon after that and it progressed.”
The nuns who handed Monaghan over for adoption refused to be interviewed by Sixsmith.
Instead they sent him a letter saying her adoptive father had previously been cleared to adopt in California.
They also claim that vetting was the responsibility of either the American Adoption Agency or the Catholic Welfare Bureau.
The Irish Examiner reports how "Ireland’s Lost Babies" tells how some American parents traveled to Ireland to pick up their children.
But many children, it says, were ‘mail-order’ babies who were taken without their new parents ever setting foot in the country.
The Church in Ireland set up its own vetting system, relying on local Catholic organizations in America to access the suitability of prospective adopters.
Mike Milotte, the author of Banished Babies, told Sixsmith that the vetting system run by the organization Catholic Charities was deeply deficient.
He said: “Catholic Charities, by its own admission, wasn’t up to that job and confessed very late in the day that they didn’t have the personnel, the systems, and the resources, and in many states, wasn’t even legally registered as adoption agencies.
Cork born Cathy Deasy told how the nuns at the Sacred Heart convent in Bessborough sent her with a courier to New York in 1958 when she was just four.
Deasy recalled: “They did it all by mail. They didn’t fly and pick out a child.”
Florida resident Deasy had an idyllic childhood until her sister Dolores left their New York home to go to college in California.
She added: “She decided to move to California and my parents went through an empty nest syndrome and missed her so much.
“My father said: ‘By the way we had a college fund for you but we spent it and we intend to continue spending it and we are going on a cruise and we want you out of the house by 18.’
“My adoptive parents cut ties with me when they sold their New York home and went to California to be with their biological daughter
“It was horrible to say goodbye because they were the ones who said hello to me when I got off the plane from Ireland. Even though I was supposed to be older I guess and get over it, it hurt and still hurts.”
The report adds that both Deasy and Ms Monaghan were reunited with their birth mothers in Ireland over the past 15 years and spent a number of years getting to know them before both their mothers passed away in recent years.