“I have a condition called chimerism,” explains Taylor. “Basically, it means I am my own twin.”

The first indication that there was something unusual about Taylor was present at birth – a straight line down the center of her torso divides it into two halves with different skin tones. Doctors dismissed it as a birthmark.

She began to get sick in her early teens, but doctors were mystified by the cause until one correctly diagnosed Taylor as a chimera. The rare condition occurs when two fraternal fertilized eggs fuse in the womb – in a sense, Taylor absorbed her own twin sister. She still carries her sister’s DNA and genetic makeup in addition to her own.

Watch: Is Your Body Attacking Itself?

“I have two different immune systems, and I have two different bloodstreams. My body treats my sister’s DNA and cells as foreign matter and wants to get rid of them, but it can’t,” she tells The Doctors. The result has been repeated immune flare-ups, and Taylor has multiple allergies.

Even before she was diagnosed, Taylor says, she was unusually interested in twins as a child. “I used to ask my mom, ‘Do I have a twin sister? Do I have a twin sister?’” she admits.

Since her condition is so rare it’s been hard for her to find information about it, and she’s hoping The Doctors have some tips for her. Geneticist Dr. Brandon Colby has answers for Taylor.

Watch: Finding a Cure Through Gene Mapping

Dr. Colby confirms that Taylor’s symptoms are consistent with chimerism. One of the effects of the condition is that, because she has two immune systems and a double set of DNA, she’s likely to get abnormal results on many medical tests. “It’s important for Taylor throughout life to inform doctors that she has chimerism, so when they get these strange test results back they know how to quickly interpret them correctly. This may save her life.”

Two companies that Dr. Colby works with, Sequencing.com and Diagnomics, would like to offer Taylor free genetic testing and analysis. “I’m going to be your doctor through the process,” Dr. Colby assures her, “And we’re going to create a personalized plan that will help optimize your health throughout your life.”

He also assures Taylor that chimerism is not inherited, and her children should not be affected.