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A doctor views an x-ray of conjoined twins at a hospital in Chongqing municipality, China, Jul. 27, 2010. Reuters

Carmen and Lupita Andrade were born sharing their ribs, circulatory, digestive and reproductive systems. Now 16 years old, the conjoined twins each have a heart, their own set of arms, lungs and a stomach. Along with their family, the twins chose to forgo the surgery to separate them that could result in their death.

“There’s a lot more risk to it than actually being beneficial,” Carmen told the Hartford Courant.

“[We] decided not to [go through with a surgery],” said Lupita, finishing her sister’s sentence. “We’re just going to live out life and that’s it.”

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Doctors contemplated separating them when the two were babies but found they couldn’t do it safely enough. But being fused together is fraught with health complications. Lupita has only about 40 percent lung capacity as well as a severely curved spine, according to the Courant.

“We’re so dependent on each other,” said Lupita.

The twins, however, make sure people know they’re each their own person.

"A lot of people don’t notice [how different we are], because when they first meet us, we kind of have the same reactions," said Carmen. "But our friends, once they get to know us, our friends literally tell us, 'You guys are so completely different,’ and I’m like, 'Well, yeah. We’re two different people'"

Conjoined twins are a rarity among newborn babies, occurring once every 200,000 live births, according to the University of Maryland Medical Center. Up to 60 percent of conjoined twins are stillborn, while about 35 percent survive just one day after birth. The survival rate for conjoined twins after birth ranges between five and 25 percent.

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When Carmen and Lupita were born, doctors told their parents they only had three days to live, but conjoined twins have lived for years without being separated. Ronnie and Donnie Galyon, now 66, are the oldest living conjoined twins on record. And for Carmen and Lupita, the risks that come with separation are too great.

“There’s been a person there…listening about my crap,” said Carmen. “I guess [there’s] an emotional attachment to my sister.”