It's a medical first: identical twins in the UK have undergone a live liver transplant, despite originally not knowing that they were identical until one of them needed surgery.
Geraldine Rowing's liver had been damaged by cancer a few years ago. Her health then began to deteriorate rapidly, so her doctors recommended she went on the transplant list.
At the time her sister Annemarie Atha didn't think twice about donating part of her liver to her twin sister.
Ms Atha said it was an added bonus to find out that, despite everything they had always been told by their mother, they were genetically identical, meaning her sister did not need to take a cocktail of drugs to stop her body rejecting the new organ.
Geraldine initially found out they were identical after mentioning to her doctor that she was a non-identical twin and he suggested doing further tests.
The tests revealed that the 48-year-old sisters, who live in Rothwell near Leeds, were genetically identical despite not looking exactly the same.
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"Mum always said that because there were two placentas when we were born that we weren't identical," said Ms Atha.
"So we've grown up believing we're not identical because Geraldine's got a wider smile than me and she's got a squarer face than me. We've both got the silly same nose and I'm a teeny, teeny bit taller than Geraldine. So mum always said you're not identical.
"But they said you're identical enough to do the transplant."
The sisters went through the operation in April and Ms Rowing said she is "feeling better by the day".
"It was a while ago and I still get tired but I can't thank everybody enough," she said. "I walk around and nobody knows that I've had a liver transplant."
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Ms Rowing said not having to take immuno-suppressant drugs has had a range of benefits - some obvious and some not so obvious.
She said it means she can eat her favourite soft boiled eggs and soldiers with her two young children.
Ms Atha said: "It's nice to have Geraldine back to normal again."
Consultant liver surgeon Raj Prasad, who carried out the operation, said live liver transplants - where the donor is a living person who donates a section of their organ for the operation - are becoming more common.
He said St James's did their first one in 2007 and will do around 20 this year - around one in seven of all liver transplants.
Mr Prasad said the main problem was putting the donor - an otherwise healthy person - through a major and potentially life-threatening operation.
But he said it meant the ill person did not have to wait for an organ to become available from a dead donor. And Mr Prasad said the benefits of identical twins having the operation was massive.
He said it was even more so in the case of Ms Rowing as taking immuno-suppressant drugs would increase her risk of further cancer.
Mr Prasad said: "It's an absolutely massive advantage which is God or nature's gift. It's a dream."