The condition often means constant shortness of breath, chronic cough and repeated chest infections; the lungs and pancreas of many with the disorder become clogged with a thick mucus and vital enzymes are not released to digest food, leading to malnutrition.
People living with cystic fibrosis face a dramatically reduced life expectancy and a host of other problems.
Emma said many with the disorder spent a lot of time in hospital, but she and her brother were among the lucky ones.
Cystic fibrosis had never stopped the twins, father Russell Gawn said.
"We have a family philosophy of ‘let’s just get outside, get moving, and live life’."
And the twins had been active and involved in sport "since they could walk".
Jake is a flanker in the Waitaki Boys’ High School first XV rugby team and Emma captains the Waitaki Girls’ High School First XI hockey team — it is her fifth year on the team.
And both have played a host of other sports over the years.
Although Emma said she knews she was lucky, she could not help but wonder what life would be like if she did not have the disorder.
"Jake and I are both really fit, but it’s like ‘How much fitter would we be if our lungs fully worked?
"Would it be easier to go out and run a half marathon than it is now?
"I’ll never know."
The twins’ mother, Karen Gawn, said most people who knew the twins "wouldn’t have a clue" they had the disorder.
They would not know Emma took 40 pills a day to stay on top of her health; or that the twins had been taking pills, or at least portions of them, since they were four days old; that on top of the regular hospital visits, Emma visited Starship Hospital in Auckland twice as a child.
"You wouldn’t wish it on any child, but for us it was probably easier — for want of a better word — that they both had it," Mrs Gawn said.
"Because we didn’t have to treat them differently."
Now the twins are preparing to leave for university — Emma taking a bachelor of commerce, in economics and marketing, and Jake keen to pursue sport and exercise science — and their mum says "it’s going to be totally up to them to deal with it".
Mr Gawn says he is proud of his children who have to do a lot to make sure they stay healthy.
"I think they understand that life is pretty special, so you’ve got to make the most of it," he said.
