Having One Child to Save Another

July 31, 2008— -- "What is the purpose of life?" It is perhaps the grandest question ever pondered by man and the possible answers have divided the world for thousands of years.

Marissa Ayala is pretty certain of the answer, however, at least in her case.

She was born to save her older sister Anissa who, after being diagnosed with leukemia at age 16, desperately needed a bone marrow transplant.

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After a year of unsuccessful cancer treatment and similarly disappointing public pleas to find a bone marrow match for Anissa, her parents made an unusual, controversial decision to have another child in hopes that that baby could provide the life-saving marrow.

Nearly two decades later, Anissa, 36, is perfectly healthy and owes her life directly to her 18-year-old sister, Marissa.

"It was really difficult for my parents at the time," Anissa said in an interview with "Good Morning America." "I think that having another child was something that I was really, really excited about. It gave me something to live for -- to be a big sister."

After the decision was made, her father, Abe Ayala, had a 14-year-old vasectomy reversed, and her mother, Mary Ayala, conceived Marissa. But they did not find out whether the child's marrow would match until Mary was six months pregnant.

"It was like Christmas," Mary Ayala said when she learned the bone marrow was compatible. "It was a wonderful, wonderful feeling. I couldn't believe that she matched perfectly."

While the Marissa's birth brought tears of joy to her family, it also brought sharp criticism from some who questioned the ethics of having one child to save another.

"When you have a little child who's going to be a donor of an organ like bone marrow, you have a sense that the child is being created for that purpose and really doesn't participate in that choice," Alexander Capron, professor of law and medicine at the University of Southern California told "Good Morning America."