For one woman who absorbed her twin in the womb, having two sets of DNA naturally programmed to not get along has come at a price.

Taylor Muhl is constantly under attack. She looks healthy, and to the untrained eye there’s no reason to ever think otherwise. But her body is a fascinating, non-stop, genetic battleground. Why? When Muhl’s mother was pregnant with her (and unbeknownst to her mom-to-be or doctors) Taylor had company in the womb – the embryo of her fraternal twin.

Very early on in the pregnancy, Taylor absorbed this embryo along with her twin’s DNA. The result is Taylor having a condition known as chimerism, where two different sets of DNA are living under the same flesh and blood roof.

Chimerism is very rare and frequently undiagnosed, so exact numbers as to how many people with the condition are unknown. How individuals with chimerism are specifically affected also varies greatly. For Muhl, it wasn’t until she was in her early teens that she began having autoimmune issues that saw her frequently ill.

Born with a discolored ‘dividing line’ that splits her upper torso and back into two ‘sides’, it was an overlooked sign of chimerism that was simply explained away as a large birth mark. Everything on her left side is slightly larger than on the right.

She has allergies to insect bites and medication sensitivities that are evident on only one side of her body. Even the food she eats has to be selected carefully due to the adverse reactions it can cause to her twin’s DNA.

With all of  those issues on her health radar, Muhl’s life is one that requires laser-like attention to the details that many people take for granted as just things that will look after themselves. When you’re babysitting two complete sets of DNA, things can get complicated. It’s like two lives in one body, and we all know looking after one life is tricky enough already.

Story by Jay Moon