Since the girls were 9 months old, the Robbinses had known they would die young. How did they manage? How did they keep up their spirits?
How did they live with this knowledge and still rear two spirited, creative girls who became well-rounded, well-traveled young women with close friends and committed relationships?
According to family friends, former teachers and others who knew them, the Robbinses did so at great cost, emotional and financial.
And they did something that other parents of children with cystic fibrosis would never dream of doing. They let them leave home.
* Vanessa Robbins-Burke, the outspoken twin, took the name of her fiance, Darius Burke, when they began living together about a year and a half ago.
Burke, who works for a brokerage house in San Francisco, gave her an engagement ring at Christmas. They made plans to leave April 6 for a family vacation in Hawaii with both sets of parents. He was going to propose to her formally there.
"We were going to have a small wedding when we got back," Burke said.
Instead, Vanessa, who lived her last few months with a feeding tube in her stomach, returned home on March 13 from three weeks in a hospital and was not getting better.
Burke proposed marriage to her three days before she died.
"She was sitting up in bed," he said. "I told her that when we got to Hawaii, I'd do the real thing."
Vanessa Robbins-Burke died Thursday, March 23, in her apartment in Mill Valley, Calif., a suburb of San Francisco. She was 25.
* Charlotte Robbins-Sylvester majored in art for three years at Pepperdine University in Malibu, Calif., where she met a young lawyer, Caleb Sylvester.
They were married in August 1998 and honeymooned for 12 days in Hawaii. When they returned, she had to be taken straight from the airport to a hospital, where a feeding tube was inserted.
She told friends that the days in Hawaii with her new husband were "the happiest I've been in my whole life."
Charlotte Robbins-Sylvester was a few weeks shy of her 25th birthday when she died Nov. 11 - also a Thursday - at Marin General Hospital in Greenbrae, Calif.
* The Robbinses lost their only children to an incurable genetic disease that now affects about 30,000 children and adults in the United States, according to the Cystic Fibrosis Foundation.
It is the most common fatal hereditary disease among people of European descent in this country. Victims' median life expectancy is 32 years.
Of the more than 10 million people in this country of European descent, 1 in 28 is an unknowing, symptomless carrier of the defective gene.
To contract the disease, a person must inherit a defective copy of the gene, one from each parent. Each time two carriers conceive a child, there is a 1-in-4 chance the child will have cystic fibrosis, a 1-in-2 chance the child will be a carrier, and a 1-in-4 chance the child will not be a carrier.
The Robbinses knew none of this when their twins were born.
"No one else that we know of in the family has the gene," Pat Robbins said. After learning of her girls' illness, she decided not to have more children. "I think I made the right decision," she said.
* The babies were two months premature and went into intensive care, Charlotte for a month and Vanessa for two.
Pat Robbins did not want her daughters to be bottle fed, so she pumped her breasts and sent the milk to the hospital.
That was in Lexington, Ky., where Jeff Robbins was studying at the University of Kentucky to become a veterinarian. A Vietnam veteran who grew up in the Frankford section of Philadelphia, Robbins, now 52, is from a family of horse trainers.
He met Pat, now 48, an outgoing, articulate woman who grew up in Wayne, N.J., while both were students at Trenton State College.. They had been married for about a year when they became parents.
The girls were home for only a short time when their mother discovered that their skin tasted salty, a symptom of cystic fibrosis. She learned that by kissing them.
She didn't know what the problem was, but she was concerned enough to take them to a doctor. When tests disclosed cystic fibrosis, Pat Robbins had trouble accepting it.
"When they told me, I thought they were going to die any day," she said. "I was afraid to love them, so I cried all the time. It was very, very hard."
She sought counseling. Her husband began a string of countless sacrifices the couple made; he dropped out of graduate school.
"They totally, 100 percent, dedicated their lives to their children," said Pat Jones, a family friend from Berwyn. "Everything they earned went to the girls."
Michael Bacon, another family friend and Jones' brother-in-law, said the Robbinses were ordinary parents who responded to extraordinary circumstances.
"The girls' medical condition demanded so much more of Jeff and Pat than those of us with healthy children," Bacon said.
In 1976, Pat and Jeff Robbins moved back to the Philadelphia area, and two years later, Jeff agreed to manage a 122-acre horse farm in Chester Springs for $9,000 a year.
The girls had what their mother called an idyllic childhood. They had "every animal known to man," Pat Robbins said, including a pony named Hoover and a chocolate Labrador retriever named Hershey. When the dog had puppies, the girls gave them chocolate candy names - Snickers, M&M's, Reese's.
During that time the girls were relatively healthy. They had to be hospitalized only twice before they turned 15. Their mother had them on a vitamin-rich diet in hopes of controlling the disease.
"I really believed that if I kept them strong, they would live," she said.
The Robbinses took their daughters on vacations to exotic places like St. Thomas and the Dominican Republic. They visited Disney World six times. They made many trips to California. On one of them, Vanessa, then 16, met Burke, who became her long-distance boyfriend.
"The girls always thought that we had a lot of money," Pat Robbins said. "But basically, we spent as we went."
* Sometimes, there was nothing to spend.
In 1990, after a series of financial disputes with the owner of the horse farm, the Robbins family was evicted.
They lost everything - home, car, security. Vanessa attempted suicide. Charlotte went into a depression.
The parents still have trouble talking about it. "It was the worst time of our lives," Pat Robbins said. "We were drowning, really."
They borrowed money to live on. Eventually, they bought a house in Phoenixville financed through the Veterans Administration.
In 1994, a federal magistrate awarded the family $120,000 in compensatory and punitive damages from the farm dispute.
* Although they were beginning to deteriorate physically, the girls rallied from their depression and began to blossom again at Phoenixville Area High School.
They took part in school activities. Vanessa especially enjoyed acting. They were good students, "vibrant and energetic," said Cindy Hartson, who was their guidance counselor.
"I remember they came to me in their senior year because they wanted to be put in different classes," she said.
"But neither wanted to give up these two particular teachers. So they came into my office and started to argue, going round and round, talking in stereo, saying, 'This one is the dominant twin and that one always gets her way.'
"I finally laughed and told them it was a family problem. I handed them the schedule and told them to decide.
"They stayed together."
* The family decision that created a measure of controversy arose in 1993, when the twins graduated from Phoenixville High and wanted to go to college in California.
Pat and Jeff Robbins agonized, trying to weigh the girls' desires against their fragile health.
Initially, Hartson, the guidance counselor, was among those who opposed the idea. "As a nurturer, I was against it," she said. "But their mother had brought them up to have wings."
Charlotte went to Pepperdine in Malibu. Vanessa went first to Mills College in Oakland and later to Loyola Marymount in Los Angeles, majoring in theater.
Pat Robbins said that other parents of children with cystic fibrosis questioned the wisdom of the family's decision.
"They said, 'How can you do that?' We felt like, 'We raised them to be like other kids, so how can we not?' " she said.
"By us letting them go, they were living the lives they wanted to live."
* The girls knew of the sacrifices their parents made.
In an interview with a Bay Area television news show in July 1999, Charlotte - using the past tense - said she had "lived a really good life - until recently, then I got a lot sicker."
She began to cry, then composed herself.
"I feel my parents' pain, too, because they have to watch us go through this," she said. "They were always able to keep us healthy. I think it's hard for them to accept that now they can't."
* Knowing did not make the experience any less shattering.
"Pat, in the last year, spent a good part of her time getting ready for their deaths," said Pat Jones, the family friend. "I don't think Jeff was ready at all. He always thought they would have more time."
Pat Robbins is now director of development at Paoli Memorial Hospital. "I didn't have time to grieve after Charlotte died," she said. "I went right back to work, and I just kept my thoughts focused on watching out for Vanessa.
"Now with Vanessa dying, I'm just trying to get together all the details - for her memorial and everything."
Jeff Robbins, now a laboratory technician for Bayer Corp., said his girls' deaths "hit me at funny times. Like when I'm driving the car, suddenly this crushing type of depression will come over me."
Their lives are still centered on their daughters. There are condolences to accept, kindnesses to acknowledge. There will be a memorial service for Vanessa at 11 a.m. April 15 at St. Peter's Lutheran Church in Chester Springs.
And after that?
"I can't imagine what the rest of my life will be like," Pat Robbins said. "My whole life has been my girls. That's what I am. I'm a mom."