Twin sisters Hope and Faith may share the same body, but their parents say the newborn girls are already displaying distinct personalities.
The girls were born in Sydney this month with an extremely rare medical condition known as diprosopus, meaning they share a heart, a body, limbs and a skull, but each has her own brain and set of identical facial features.
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Conjoined twins born in Sydney
Twins Hope and Faith share a heart, a body, limbs and a skull but each have their own brains and set of identical facial features. Nine News.
There are thought to have been only about 35 recorded cases of the condition ever.
Less than two weeks after the twins' birth by emergency Caesarean section, their parents, Renee Young and Simon Howie, say the girls have begun to develop their own personalities.
"Faith tends to cry a little more, while Hope takes after her mum and likes to sleep a lot," Mr Howie told Woman's Day magazine.
"Faith blows little bubbles and loves sucking her thumb but Hope prefers the dummy."
Ms Young said the twins "are very separate" in their personalities.
"You have to see it to believe it. Sometimes Faith will cry and wake Hope up, who then looks sideways as if to say 'Thanks for that'," she said.
The parents also revealed they had faced criticism for their decision to go ahead with the pregnancy.
The couple, who were already parents to seven other children in a blended family, discovered during an ultrasound 19 weeks into the pregancy that the girls would be born with diprosopus, which is Greek for "two faces". The condition is also known as cranialfacial duplication.
Doctors told the couple at the time that they should consider terminating the pregnancy, as developmental issues meant the babies might have difficulty breathing once they were born.
But the parents decided to go ahead with the pregnancy and, at 32 weeks, Ms Young was taken to Blacktown Hospital before being rushed by ambulance to The Children’s Hospital at Westmead. The girls were born on May 8, weighing just over two kilograms.
"I try not to listen to what people have to say," Mr Howie told Woman's Day, referring to the public criticism.
"I have more important things to worry about.
"Other people's opinions don't matter, but it's sad to hear it. Maybe they are just scared of difference."
Mr Howie said their daughters' future remained uncertain, but the girls were breathing on their own.
"I'm amazed every time I walk into this room," he said.
"Each time I come means they've reached another milestone and pulled through another day.
"Each day comes with more tests and a little more knowledge, but it's all so unkown that we are all learning together as we go along."
Ms Young said she felt blessed.
"We are blessed we've got this far. I just find them adorable," she said.
Even though Hope and Faith have only one body, their parents still refer to them as their baby twins.
In the US, Missouri mother Brandy Johnson gave birth 10 years ago to her son Tres, who also has diprosopus. Ms Johnson identifies Tres as one son.
In an interview with The Daily Statesman in Missouri this year, Ms Johnson said celebrating her son's 10th birthday was a miracle and a blessing, as only a few babies with the condition have been known to survive childbirth.
But Tres's life had not been easy, she said. A test last year revealed that he experienced up to 120 seizures a day. He had also been implanted with a stimulator that shocked his body.
"He has to be resuscitated four to six times per week," Ms Johnson told The Daily Statesman. She said it was not full CPR, but rescue breaths to keep his airways sufficiently opened up.
"He's died in my arms twice," she said.
Ms Johnson has given her son a type of cannabis oil, which she says has drastically reduced her son's seizures.
She has joined a campaign lobbying for the decriminalisation of the use of marijuana for medical purposes in Missouri.