Siblings Peter, Kate and Charlotte Cipolletti have never run a marathon before, but when they take the starting line for the Boston Marathon, it will be personal.

Just over a year ago, they lost their sister, Emily, to hypoplastic left heart syndrome (HLHS), a congenital condition that affects normal blood flow through the heart due to underdevelopment.

Emily Cipolletti died just over a year ago from hypoplastic left heart syndrome (HLHS), a congenital condition that affects normal blood flow through the heart due to underdevelopment. The Cipolletti Family

"I thought that, for me, a way to honor Emmy, and pick up, move on and channel her, was to do something courageous and really difficult," said Charlotte, 23, who works in portfolio management for an asset management firm in New York.

The siblings were raised in Boston as part of a family of 12, 10 siblings and their parents. They reminisced about living in a large family, and said they'd never have it any other way. For Peter, the third-oldest, the chaos is something he loved and on which he thrived. For Kate and Charlotte, growing up with eight other siblings meant having nine best friends for life. They wondered what it would be like to have only one sibling and not get along with them, or what dinner would be like without the noise.

"It's something that always comes up in conversation, something that is so important to know about us," said Charlotte, the ninth sibling. "Being one of 10 kids requires you to become your own individual amongst the crowd, and it is something that shaped each one of us."

It was in Boston at the Children's Hospital that Emily -- the eighth child -- endured a three-stage open-heart procedure immediately after her birth, the last one of which involved high risk and experimentation. The surgery was successful, and Emily went on to live for 24 years.

"Knowing Emily, you'd have never known she had this devastating heart condition," said Peter, 37, who lives in Duxbury, Massachusetts. "She has this funky personality. She was the kind of person, when she walked into a room, everybody fell in love with her."

Said Kate: "She was 1,000 percent herself 1,000 percent of the time, and I use that percentage because she was that extreme. She would sweep you up in her force field."

In 2010, she had what the doctors thought was a heart attack. On March 24, 2016, six weeks after a freak car accident where she passed out behind the wheel, she died in her sleep.

The cardiologists and neurologists were flummoxed. Emily seemed fine, but there was a missing piece in the puzzle that couldn't be detected, Kate recalled. All the siblings could think about was this: If only the hospital could have figured out what was wrong in those six weeks between the car accident and her death.

"We weren't supposed to have 24 years. We were supposed to have a year with Emmy, so that's like a huge thing for us. Emmy is a gift," Kate said. "If we can give kids like her the gift of life, that would be incredible and that's why we wanted to run."

And after feeling like "a three-mile run used to be a huge accomplishment," they will be at the starting line on April 17, running as part of Boston Children's Hospital's Miles for Miracles team. They have already raised $47,000 for cardiac research and awareness, and hope to reach $60,000 before Marathon Monday.

Apart from raising money for Miles for Miracles, the siblings also raised $50,000 for Emmy's Angels, a charity organization they launched for cardiac research and awareness.

Charlotte was the key force behind getting the siblings to run the marathon. Although they were contributing to HLHS, they all wanted to be physically involved in some way, and that's when they came across Miles for Miracles. Charlotte pitched it to her siblings, and Kate and Peter immediately said yes. From there they went through rigorous training during the Boston winter but found a way to heal during the process.

"Running the Boston Marathon made perfect sense, because it has so much history and it is so much bigger than ourselves," Kate said. "Emmy's heart condition and her passing means something and we wanted it to represent something bigger than our family."