Dee Ann Angell was used to the jokes and the sneering she had to put up with at school. Blonde-haired and blue-eyed, she would be teased because she looked so different from her brown-eyed brunette siblings.

"Did your mother go with another man?" her friends would say, and she would just laugh and brush it off.

Kay Rene Reed would sometimes hear a rumour in her family that a terrible mistake had been made at birth and she had been switched with another baby.

That explained why she looked so different from her siblings, so the rumour went. But she too dismissed it and moved on.

Fifty-six years after the two women were born on the same day in 1953 they no longer dismiss anything. Through DNA testing they now know they are not who they thought they were, that their lives have been led, cuckoo-like, in the wrong nest.

Each weighed about 6lbs (2.8kg) at birth on 3 May 1953. Each was hairless. They were the only two babies delivered that day at the tiny Pioneer Memorial hospital in Heppner, Oregon. A nurse took them both to be bathed, sharing the facilities for convenience's sake, then returning them to their mothers.

They were taken to homes 20 miles apart and in the course of time married and had children and grandchildren of their own. Their paths never crossed again until earlier this year.

The truth began to emerge last summer when a neighbour of Marjorie Angell, Dee Ann's mother, divulged a secret she had been carrying inside her for years. Aged 86, the unidentified neighbour had waited until all four parents of the women had died, keen to avoid inflicting distress.

Now she came forward and confided in one of Kay Rene's brothers that while still alive Marjorie had told her that the babies had been mistakenly switched at birth.

When the nurse brought back the babies from bathing them Marjorie had cried out, "This is not my baby!" But her protests went ignored, and she had spent the rest of her life privately convinced she was raising the wrong child.

When Kay Rene heard the news it rang a bell for her. Her own mother, Donalda Reed, who had been heavily sedated giving birth and had never harboured doubts, had only once referred to the rumours that had occasionally swirled around the family. She told Kay Rene they were not true. "You are my daughter and you always will be," she said.

But those doubts were now impossible to put down. The two women contacted each other earlier this year and arranged to meet. One of Dee Ann's sisters, Juanita, joined them and for Kay Rene it was like lightning had struck. They were identical. "That's me!" she exclaimed, pointing at her natural sister.

Juanita replied: "There's no point having a DNA test, just look at us!"

They did go ahead with a test, and as they awaited the results they cracked jokes. "Who's my mama?" shouted Dee Ann, "Who's my daddy?" echoed Kay Rene.

The test measured the genetic possibility of Kay Rene being related to her brother and sister: zero. It also tested the genetic possibility of her being related to Dee Ann's brother and sister: 99.99%.

The few weeks since the discovery have been an emotional roller-coaster for both women. In part it has been a bereavement, a coming to terms with the fact that they will never meet their natural parents, that the lives that had been intended for them have been irretrievably lost.

"It's sad," Dee Ann told ABC television today, close to tears. "I think that I missed out on knowing my own parents, my own family."

Kay Rene described feeling intense guilt, that she had stolen the other woman's memories. When she looked at her family now she felt "I have cheated them - it shouldn't have been me. I'm glad it was because I've had a wonderful life."

But another part of the experience has been hugely enriching. On their 56th birthday earlier this month the two families came together for the first time. It was as if each woman had been given a gift of a second family. "We just had a ball together," Kay Rene said.

There is also the gift of friendship that has been forged between the two. They call each other "twisters". They have shared notes about each other's lives that have revealed strange intimacies. Dee Ann grew up loving horses which was unlikely in her family that had no tradition of riding; she learnt that Kay Rene had been brought up on a ranch by her father who saw himself as a cowboy.

Kay Rene cracked chewing gum in a distinctive way; when she met her natural sisters for the first time they did likewise.

The ups and downs continue. The hospital that made the switch has offered them counselling to ease the trauma, but they politely declined. "We are old women now," said Kay Rene.