A simple cold could land Carmen and Lupita Andrade in the hospital. The girls are like any other teens — they worry about grades and hang out with friends — except the two are conjoined twins and Lupita can only use about 40 percent of her lung capacity, reports the Hartford Courant.

Read: Autism Treatment 2017: Brain Imaging Could Diagnose Disorder Before Symptoms Appear, Enable Early Intervention For Kids On Spectrum​

Their mother, Norma Solis, tells the paper she gave birth to the girls in June 2000 in her native Mexico, where doctors told her the twins would only live for three days. Solis and her husband looked into operations to separate Carmen and Lupita, but it wasn’t possible as the girls share organs. Utilizing an organization called Healing the Children that provides kids from around the world with access to medical care, Solis brought the girls to the United States. Unfortunately, doctors in the U.S. were also unable to safely perform the surgery to separate the girls.

But now the family is looking into an operation to fix Lupita’s scoliosis and straighten her spine, which would help with breathing. According to the Courant, Dr. Mark Lee tells the family the surgery comes with great risks, but leaving the scoliosis go untreated does too.

"The worst-case scenario is that you die from the surgery and that's a possibility," Lee said in the Courant. "Short of losing your life, you can lose neurologic function. If you lose neurologic function and one or both legs don't work, you'll know about it right away.”

Despite the complications from being conjoined, the girls are able to tackle everyday tasks like learning to drive. Carmen is currently practicing to get her driver’s license.

"The reason I want to get my license is to be more independent," Carmen told the Courant, "so I won't have to rely so much on my parents."

The twins spend a lot of time in their high school’s agriculture department and hope to work with animals someday, perhaps as veterinarians, reports the paper.

While it seems like there’s always lots of talk about separating conjoined twins, Carmen and Lupita enjoy being together.

ReadWhich States Are The Best And Worst For Kids' Health? New Survey Results For All 50 States

"There's been a person there for, like, my whole life, listening about my crap ... I guess [there's] an emotional attachment to my sister,” Carmen told the Courant.

According to the University of Maryland Medical Center, conjoined twins occur when a woman produces only one egg, and it begins to split into identical twins but stops before completion. Extremely rare, it only occurs in about every one in 200,000 births.

See Also:

Which Countries Have The Fussiest Babies? Infants In The UK, Italy And Canada Cry The Most; Here's Why

The Evolution Of Childbirth — And Why One Million Babies Die The Day They’re Born: Gates Foundation Letter