Woman Born With An Unusual Birthmark Discovers She Is Her Own Twin

From the moment she was born, Taylor Muhl stood out from other people. That’s because she has a very unique birthmark, which runs right down the middle of her body. The effect is that one half of her torso looks a different color to the other. It’s a cool, unusual quirk, but she was absolutely shocked when she learned the real reason for it.

A straight line

The birthmark itself has a reddish hue, which really stands out against the paler color of the rest of her skin. But it’s not just the shade of this feature that’s surprising, as it also runs in a really straight line. You’d expect a birthmark to have quite an irregular shape, but this one is really precise.

A larger left side

On top of that, Taylor also has some other features that are quite unusual. Writing on her own blog, she explained, “Everything on the left side of my body is slightly larger than the right side. I have a double tooth in the left side of my mouth and many sensitivities and allergies to foods, medications, supplements, jewelry, and insect bites.”

Two sets of DNA

The unusual features don’t end there. Taylor once went to see a doctor, who was an expert in conditions deemed to be especially rare. This doctor revealed something incredible about Taylor: she apparently possessed two different sets of DNA. “Not only that,” she explained on her blog, “I’ve been told I have two immune systems and two bloodstreams.”

Her own twin

That must have been quite a shock for Taylor to hear. And it must have been downright confusing — how can a person have enough DNA, immune systems, and bloodstreams for two people? Well, the truth is genuinely strange. From a certain perspective, Taylor can be considered to be her own twin.

A normal life

Taylor had lived a pretty normal life before learning this strange fact about herself. Despite the unique issues she faced as a result of her physiology, she was a very active person who took up dancing in her youth. She later moved into music, writing and singing her own songs. She’s also done some modeling.

Grandpa Muhl

It shouldn’t have been much of a surprise that Taylor was attracted to show business, given her lineage. Her grandpa, it turns out, was a prominent producer in Hollywood named Edward Muhl. He was a bigwig at Universal Studios for a long stretch between the ’50s and ’70s, working on classics including Psycho, To Kill A Mockingbird, and Spartacus.

Making headlines

With a grandfather like that, it’s no surprise Taylor set out for a career in the spotlight. And certainly, she has made headlines in recent times. Yet so far, that has more to do with her unique physiology than anything else. In 2016 — a little while after learning the truth about herself — she started to speak publicly about it.


Having grown up being told the feature on her torso was simply a birthmark, Taylor found out the truth was far more complicated than that in 2009. There was a specific reason for this trait and also for the issues she experienced with her immune system. Taylor’s characteristics, it was finally explained to her, were a result of chimerism.

Absorbing the other

So, it was Taylor’s chimerism that accounted for her two DNA sets, immune systems, and bloodstreams. But what is chimerism, exactly? Well, it’s something that happens when twin fetuses are developing inside a woman’s womb. Basically, one of these fetuses “absorbs” the other. In this particular instance, the dominant twin was Taylor.

None the wiser

Taylor’s mom had never even known she was carrying twins. It was really early on during her pregnancy that one of the fetuses had fused with the other. What this meant was that the fetus that would eventually develop into the person we know today as Taylor had actually taken on her twin’s genes.

A rare thing

This process is hyper-unusual in humans: no more than 100 cases have ever been recorded. Perhaps if Taylor hadn’t specifically gone to see a doctor who was so specialized in genetics and rare medical conditions, she might never have learned the truth.

Easy to miss

It’s very possible there are other cases of chimerism out there that haven’t been identified. After all, it’s not easy to pinpoint. Some people who have the condition might not exhibit any signs of it all, which means it can definitely go unnoticed. Even Taylor, who had some very visible signs of it in the form of her “birthmark,” went years without a diagnosis.

Finally making sense

When she finally did receive her diagnosis in 2009, Taylor felt a sense of relief. Speaking to People magazine about it, she said, “I felt freedom [after the diagnosis] because for the first time in my life I knew why my stomach looks the way it does. Prior to that, every doctor said my stomach must have just been a birthmark… Finally, this is making some sense.”

Tetragametic chimerism

In Taylor’s case, we can see a specific form of the condition known as “tetragametic chimerism.” This affects fraternal twins, in situations where two individual eggs are fertilized by two individual sperm. The two resulting zygotes then merge and a single human being eventually develops.

A normal life

All of this happens at an extremely early stage of the pregnancy, and the person that results from it can go on to live a normal life without any indication whatsoever that anything unusual has occurred. The pigmentation of their skin, perhaps, might be altered, but other than that, they’d basically be like anyone else. It’s only after a blood test that they’d ever become aware of it.

Not 50-50

Even though a person formed in this way has two sets of DNA in their body, one of these usually dominates the other. In other words, these people don’t derive half their DNA from one zygote and the other half from the other. It’s usually skewed more towards one over the other.


If the two zygotes were of different sexes to each other, the person who develops might be born with ambiguous genitalia. In other words, their reproductive organs would be neither obviously male nor female. In Taylor’s case, her twin had also been female, so this situation didn’t apply.

Allergic reactions

Still, Taylor does experience issues stemming from her chimerism. Her immune system registers her twin’s DNA as being “foreign,” which has led to autoimmune issues. In practical terms, that means Taylor is allergic to lots of different foods and medicines. She even reacts to certain jewelry, while getting bitten by insects can also be problematic for her.

Her particular case

On her blog, Taylor elaborated a little on this idea. She explained, “With my particular case of chimerism, my doctors believe my body reacts to my twins’ DNA and cells as foreign matter. Because of that, it compromises my immune system making it lower than the average person, causing me many autoimmune health issues.”

Keeping it quiet

Taylor has spoken about her relief at learning the truth behind her physiology, but she was initially worried about how others might react to it. As a person working in show business, she feared she might be stigmatized for it. So, she initially decided to keep the news to herself and her loved ones.

Raising awareness

But in 2016 Taylor decided to speak out about her chimerism. In doing so, she became the first individual working in show business to publicly identify herself as having the condition. She decided to do this in order to raise awareness of it and to help people living with it to feel okay.

Overwhelming pressure

Speaking to website Business Insider, Taylor explained, “I felt it was important to show my entire physical demarcation because in the entertainment business there’s an overwhelming amount of pressure to appear physically perfect, or within a certain physical stereotype.”

Pursuing dreams

Taylor wants to see people like her being accepted by society. She said, “I hope by showing my own imperfections I can inspire others who have physical abnormalities or who are different, to never let that stop them from pursuing their dreams, to love themselves unconditionally and to know they’re beautiful just the way they are.”

Chimerism going viral

Taylor really put herself out there in order to raise awareness of chimerism. Her first experience in the spotlight in this regard came in 2017 when she appeared on the show The Doctors. This appearance was uploaded to YouTube and became a viral hit, racking up views into the millions.

Getting the word out

That appearance was only the beginning for Taylor and her mission to raise awareness of her condition. She has featured in some pretty prominent newspapers, such as The New York Times. She’s also shown up on other TV shows, too, including Megyn Kelly Today. Lots of people have now heard her story.

A positive impact

Who knows the effect Taylor and her advocacy work might have? It’s possible people who share the condition with her might see her story and recognize it in themselves. It’s true that not many people live with chimerism, but it’s likely to be more widespread than it seems at the moment.

Other tales

While Taylor has been gaining lots of recognition, her story isn’t the only one related to chimerism that’s ever made the headlines. A couple of decades back, for instance, a woman by the name of Karen Keegan got in trouble because of it. She required a kidney transplant, which led to her and her family undergoing lots of tests.

Not a match

Long story short, these tests had revealed something strange: Karen, it seemed, wasn’t the biological mother of her own kids. That was a shocking and confusing revelation, but it was finally resolved when experts figured out she’d experienced chimerism. Basically, her twin’s DNA inside her body didn’t match the DNA of her kids. That was what had led to all the confusion.


If chimerism was more widely known about, perhaps Karen wouldn’t have had to go through such a stressful experience. And that’s at the heart of Taylor’s advocacy. She wants to raise awareness of chimerism and also to help her fellow chimeras to feel accepting of themselves and to live happy lives.