Sept. 8, 2006 -- For an episode of the TV series "Nip/Tuck," guest star Reba Schappell had to convince her sister Lori to go into show business with her.
They played conjoined twins who had agreed to be separated because one was dying of cancer.
In real life, the Schappells are well known for appearances on TV, in documentaries, and in the film "Stuck on You."
Reba is the actress. She also has recorded country music.
Lori doesn't consider herself part of that world. But if Reba wants a part, Lori has to be there, too.
At the age of 45, the Schappell sisters are believed to be among the oldest living conjoined twins in the world.
If one died before the other, they say, the survivor would choose separation — but only under that circumstance.
Otherwise, Lori said, "We would choose not to be separated. God has a purpose for every human being he puts on this Earth. He makes them in his own image. And he made us in his image. And who are we to question what God made?"
The Schappells are among a small percentage of conjoined twins who are joined at the head.
Because their heads face opposite directions, they have seen each other only by using mirrors.
Reba was born with a spinal defect and cannot walk. Lori wheels her sister on a specially made chair and spends most of her time standing.
They have distinctly separate personalities.
The example they've set with their lives has influenced how some experts think about a decision many take for granted: that conjoined twins should be separated if possible.
"I think most people feel like that's the only option," said Dr. Alice Dreger, a bioethicist and medical historian at Northwestern University's Feinberg School of Medicine.
"What really surprised me is when I looked back through history, I found that over and over again they [conjoined twins] said that not only were they OK with being conjoined, many of them actually felt that this was a superior state — that this was better because they went through the world with somebody with them, with somebody very close to them."
After their birth in September 1961, the Schappells were placed in an institution for mentally disabled people, even though neither twin is mentally disabled.
"When I had visitors," Reba said, "I would have them sneak me stuff, books."
The twins gained their independence with the support of social workers.
They now live in a private apartment complex, where each twin has her own space.
"We're different in every way," Lori said. "Even when we bathe, I like to do it in the morning. … [Reba] likes to do it at night."
They use a shower curtain as a divider so that the twin who isn't bathing can avoid getting wet.
Lori doesn't have pets, but Reba does — a dog named Mimi and a set of turtles, including one named Valentine.
When asked whether their lives were more or less complicated than other people's lives, Lori said, "Less."
"The conjoined twins that I've studied say that in fact, the way that they feel about themselves is that the body that they were born into is the body that is theirs," Dreger said.
"And in that sense, it's a normal body for them."
It's also normal for each of them not to trespass on the other's space.
Lori's part of their apartment is disorganized; Reba's is neat. And they respect that division of territories.
Lori says she has had boyfriends throughout her life. Reba doesn't interfere.
"She can't see us, anyway," Lori said. "If we're on a date, she will bring something along that she has to do, or else she'll read. She totally blocks us out."
"Conjoined twins, twins through history, have had romantic lives," Dreger said. "They're like other people. They want to have love. They want to have sex. And they do that."
Why are their personality differences so dramatic?
"Twins do what the psychologists call 'individuation,'" Dreger said.
"It means that they unconsciously develop aspects of difference between themselves so that they're able to have distinct identities. Those things allow them to develop individuality even within the space of sharing a body together."
Even when Lori overspends, Reba, who is conservative with money, doesn't interfere and may even help pay her sister's creditors.
"Lori and Reba respect each other's individuality in the way that conjoined twins typically do," Dreger said.
"They give themselves the space to make mistakes. Because that's how you have to live with somebody that you're really close to. You can't live with somebody and criticize them all the time and survive conjoined."
"You live the best way you know how, the best way you can," Reba said. "And for me there is never an 'I can't.' You have to control this. This doesn't control you … us. You control your own destiny. You control your own way of life."
Both believe in an afterlife in heaven.
When asked whether they still will be together then, Lori said, "Probably not. We'll probably be totally separated by then, because when you go to heaven you're completely healed of all your illnesses. I believe you are whole again. You're totally … one."