The NHS has admitted to accidentally swapping two baby girls at birth more than 50 years ago in the first documented case of its kind in its history.
Two families in the West Midlands are still awaiting compensation two-and-a-half years after the health service first admitted liability.
Joan, 83, discovered she had brought the wrong baby girl home from hospital 57 years ago when her son, Tony, happened to take an Ancestry DNA test.
After listening to the first series of The Gift on BBC Radio 4 last year, Joan got in touch with presenter Jenny Kleeman to share the story.
Tony, 67, had been given the DNA home-testing kit for Christmas in 2021, which he took two months later out of idle curiosity on a dreary February day after his round of golf had been rained off.
The results pinpointed the place in Ireland where his maternal family came from, but when he looked at his sister's name it was "wrong" - another woman's name was listed as a full sibling.
Tony used Ancestry's private messaging function to contact the mystery woman.
Claire, not her real name, had been given an AncestryDNA test as a birthday gift from her son, which had found no connection to her parents' birthplaces and a genetic link to a first cousin she did not know.
When Tony took his test, she received a notification that a full sibling had joined her family tree.
Through messaging, the pair discovered that Claire had been born around the same time and in the same hospital as the sister Tony grew up with.
A couple of weeks after making the discovery, Tony wrote to the NHS Trust that oversees the hospital where the two baby girls were born.
The Trust admitted liability for the babies being switched, yet two and a half years later the family are still waiting for the offer of compensation the NHS promised would be finalised last year.
Claire said in a way the surprise discovery had made perfect sense as she never felt as though she belonged.
She told the BBC: "I felt like an imposter. There were no similarities, in looks or traits. I thought, yes - I'm adopted."
Claire said from the moment she saw Joan, it felt like they had always known each other: "I looked at her, and I said, 'Oh my God, I've got your eyes! We have the same eyes. Oh my God, I look like someone!'"
While the sister that Tony grew up with did not want to take part in the programme, Joan said she had reassured her they would always be mother and daughter.
In response to a 2017 freedom of information request, the NHS said there were no documented incidents of babies being sent home with the wrong parents.
Since the 1980s, newborns have been tracked with radio frequency identification (RFID) tags issued immediately after their birth. Before then, maternity wards relied on handwritten tags and cards on cots.
Radio 4 contacted NHS Resolution, the body that determines how complaints against the NHS should be resolved, who said: "We extend our deepest apologies on behalf of the hospital involved, for the appalling error made by the NHS in the 1960s and the distressing, longer-term consequences of this.
"This is a unique and complex case, involving multiple parties whose confidentiality and privacy must be paramount.
"Legal liability was admitted immediately on receipt of the claim, and we have since been working closely with the legal team acting for those affected to agree on the amount of compensation due."