Anthea Ring, now an 81-year-old grandmother, was nine months old when she was abandoned on a hillside in southern England, in August 1937.
She was found by a family walking over the South Downs. She was hidden deep in a blackberry bush.
The blonde-haired little girl, who was wearing a pink dress, had her hands tied and was covered in scratches and bites.
Ms Ring was adopted some months later, by a family who had lost a daughter in a car accident three years before.
It was only when she was married, with a daughter of her own, that Anthea learned from her adoptive parents that she was the “Blackberry Baby”.
In 1994, Ms Ring joined a group called Norcap, who help adopted adults find out more about their past.
She discovered how she was found and cared for, but there were no further breakthroughs, until 2012, when she started using DNA tests and researching family trees.
She discovered her mother was an unmarried woman from Co Mayo. Julia Bell, a genetic genealogist, helped her to narrow her search for her father to six brothers from the Coyne family, in Co Galway.
Four of the brothers, Michael, Martin, Patrick, and Phillip, were labourers in London in 1936.
Tests on Michael and Martin ruled then out, but neither of the other brothers had direct descendants.
Ms Ring contacted Dot, a niece of Patrick and Phillip, who had letters that Patrick had sent her.
Saliva on a stamp confirmed that Patrick, who had died some years previously, was her father.
Ms Ring, who lives in Bradford-upon-Avon, is now in contact with Patrick’s wider family.
“I am delighted to have found the final piece of the puzzle of my family history,” she said.
“I can now finally tell my children, and grandchildren, about their roots, and where they came from.”
Ms Bell said Ms Ring was now in happy contact with the Coyne family, but chance had nothing to do with the discovery.
“It was not a lucky match, as some people believe. We worked very hard, using DNA and genealogy research, to establish the link.”
Galway-based historian, Catherine Corless, said she helped Ms Bell link up with the different families on the father’s side.
“Anthea knew absolutely nothing, three years ago, about who she was or where she came from,” said Ms Corless.