06/22/2009 at 01:00 AM EDT
The last time Anissa Ayala got mad at younger sister Marissa, she was at a loss for words. "The worst she could come up with was 'poopy butt,'" says Marissa, 19, laughing. Anissa, 37, joins in and adds, "I couldn't say anything really mean to her. I wanted to, but I just couldn't." Call it a perk that comes with having saved your sister's life.
At age 16 Anissa developed an aggressive form of leukemia. Her only hope was a bone marrow transplant, but no one in the immediate or extended family (including brother Airon) was a match. "We were devastated," says mom Mary Ayala. "Then I had a dream. In this dream I saw a child." She and husband Abe put their hope in a yet unconceived baby. "It was a crazy idea," says Anissa. "My mother was 42; my father had had a vasectomy; and the odds for a match were less than 25 percent." But the gamble paid off: Born April 3, 1990, Marissa was a compatible donor.
The story may be familiar to viewers of a film opening June 26, My Sister's Keeper, in which Abigail Breslin plays a girl born to donate bone marrow to a dying sister. The plot comes from a 2004 novel by Jodi Picoult, but echoes the loud ethical debate that ensued when the Ayalas' story went public. "It never entered my mind that people would think it was controversial," says Mary, 62. "I still would have gone ahead with it, but I would have been more prepared."
A 1991 TIME cover story reported that some felt the family's decision evoked "baby farming, cannibalizing for spare parts." But the Ayalas never saw it that way. "She's my baby sister," Anissa said at the time. "We're going to love her for who she is, not for what she can give me." Still, threats of death and kidnapping followed. "Those were scary times," she recalls.
In some ways the family were both medical pioneers and historical footnotes. "What the Ayalas did doesn't happen anymore," says Dr. Arthur Caplan, a medical ethicist at the University of Pennsylvania. In 1990 the donor registry had only 17,000 names. "Today there is a gigantic national marrow donor program where you'd find a match for many people. You wouldn't have to have a baby." Also new drugs like Gleevec, which kills off abnormal blood cells, mean fewer leukemia patients need marrow transplants.
Today Anissa remains cancer-free and is a development director for the Leukemia and Lymphoma Society, through which she has started the Marissa Eve Ayala Research Fund (lls.org). She and her fiancé, Robert, reside close to her parents' Walnut, Calif., home, where Marissa lives while studying to become a teacher. Cancer treatment left Anissa unable to have children, but with a 17-year age difference, says Marissa, "she's like my second mom." Of the event that made her briefly famous, she says, "I don't remember a thing about it." The soft-spoken teen downplays her role in her gregarious sibling's recovery, saying, "I'm not special because I gave her bone marrow. We're both special because of the way we connect." Adds Anissa: "She's not once said, 'You owe me.' I've been so lucky to have a life. And even luckier that Marissa's in it."