The Trebing children - Calvin, Katie and Christopher - sat on the porch of their Nesconset home, looking like any other children slurping Coke floats and ice pops under an Easter Sunday sun.
But two of these siblings share a bond more special than most - a lifesaving bond forged three years ago in a hospital room.
Seven-year-old Katie was born with Diamond Blackfan anemia, a rare blood disorder that kept her body from making red blood cells. Her only hope for a cure was a risky bone marrow transplant, using marrow from a compatible sibling donor. Calvin, now 10, wasn't a match.
So in a move some saw as fraught with ethical concerns, Katie's parents, Steve and Stacy Trebing, created a third child using embryonic testing to ensure the baby would be a perfect match for Katie.
The Trebing's story is being retold now in a book being published this month, and in television and radio appearances the family is making.
"It was definitely surreal," Steve Trebing said. "I didn't think it was possible. You watch all these movies, and you're like oh, yeah, it's science fiction. But when it was presented to us, I was almost shocked. Was it real? Could it really happen?"
If all went well, Christopher would suffer no ill effects and Katie would be completely cured. There would be no more blood transfusions that Katie relied on to survive, and, more crucially, she would have a better long-term prognosis.
But the transplant process carried its own risks. To ready her body to accept the marrow, Katie would have to endure chemotherapy that would destroy her immune system.
"The risk is that she would die, really," Stacy Trebing said. "That's a big risk."
But the Trebings decided to go ahead with the transplant. In May 2006, using marrow removed from Christopher's hip bones, doctors at Memorial Sloan-Kettering dripped the fluid into Katie's system. The transplant took. Katie was free of the disease.
Because the Trebings don't believe that embryos at such an early stage can be considered as children, they didn't have a concern about choosing the best ones as a match for Katie, Stacy Trebing said. And once Christopher was born, the couple didn't believe he would "feel negatively because of what has happened, but we never really thought he would because we were just so happy to have him," she said.
Katie's transplant doctor, Dr. Farid Boulad, medical director at Memorial Sloan-Kettering's Pediatric Day Hospital, said in an e-mail that Katie is "doing very well" and is "cured."
The Trebings say the cloud has finally lifted. "I used to think about it all the time," Steve Trebing said. "Daily."
Now Katie's days are taken up with school, gymnastics, soccer and cheerleading, not doctors and hospitals.
She still must undergo twice-yearly testing for the rest of her life, in case the chemotherapy had harmed her organs. The result of a recent heart test has been slightly abnormal, Stacy Trebing said, but doctors have opted to wait and watch.
Meanwhile Katie, an energetic first-grader at Tackan Elementary School in Nesconset, is happy to talk about her story.
"I didn't have enough blood. Then Christopher gave me blood and I got better," she said.
Now, Katie said, "I feel super," jumping up and spreading her arms in a cheer.
The Trebings have been sharing their story publicly, saying they hope that it will help others.
Stacy Trebing sometimes speaks at bioethics classes about the Trebings' decision, and Steve Trebing plans to compete in a half-Ironman triathlon this year to raise money for research on the disease.
"We've already had an e-mail from a family that wanted to remain anonymous, and they just started the same journey," Steve Trebing said. "They said, 'Thank you, thank you, thank you.' And already it's worth it."
The Trebing family will be at The Book Revue, 313 New York Avenue, Huntington, at 7 p.m. tonight to discuss their successful effort to save their daughter, Katie, from the rare disorder, Diamond Black Fan Anemia, by conceiving a child who would be a match to donate bone marrow. The case is the subject of a new book, The Match: "Savior Siblings" and One Family's Battle to Heal Their Daughter, by Newsday staffer Beth Whitehouse, who also will speak tonight.