In Greek mythology, a chimera is a female creature made up of three different animals. In reality, chimerism is no where near as horrifying or mystical; it is simply when one organism is made up of at least two different genotypes, or two separate sets of genes.
We know animals can be chimeras, like anglerfish who use it during procreation or a cat with a perfectly halved face. But can people be chimeras? Yes, but it is sometimes not as obvious as it is with the rest of the animal kingdom. Humans who are chimeras have two different sets of DNA or blood types. Genetically, a chimera woman is her own twin sister, and a father can be his son's uncle. Individuals who are chimeras can suffer devastating effects legally and physically due to their mixed genetic makeup. It's also rarely documented but likely a lot more common than we think.
A Woman Was Found To Have Two Of Almost Everything - Even Skin Colors
Taylor Muhl sought out the opinion of a doctor after noticing a reddish "birthmark" covering the left half of her torso. She also noticed that everything on that side of her body was larger or had sensitivities or allergies not present on the right side.
The doctor diagnosed Muhl with tetragametic chimerism, which occurs when two eggs are fertilized by two different sperm and then one of them absorbs the other. The result in this case is two blood types, two immune systems, and two skin colors on the torso.
A Chimera Mother Had To Prove She Was The Biological Parent Of Her Children
When applying for benefits for herself and her children, Lydia Fairchild had to provide a DNA sample from herself and her brood to prove they were related. The tests came back showing that Fairchild could not be the biological mother of her children.
Even after witnessing Fairchild give birth, the Department of Social Services threatened action since the DNA proved the kids were not her own. In fact, the DNA tests revealed that her twin sister was actually the biological mother of her children... except Fairchild did not have a twin.
After learning about another woman that had two different DNA types in her body, it was concluded that Fairchild was actually her own twin due to chimerism. Further testing was done and Fairchild was finally proven to be the biological mother of her children.
A Chimera's Unborn Twin Brother Fathered His Son
A man used his semen with a surrogate mother to carry a child for himself and his partner. However, after the child was born, blood tests showed that their son was not biologically related to either one of them. The couple had the child's DNA tested, and the test revealed the child only had 10% of the same DNA as the donor father. Naturally, the couple began to wonder if the fertility clinic had made a mistake.
Additional testing showed that the donor father was actually a chimera; the DNA in his sperm was only 10% his own, while the other 90% was actually from his unborn fraternal twin. Vanishing twin syndrome is the cause of most known cases of chimerism. According to the American Pregnancy Association, Vanishing twin syndrome happens when "a twin or multiple disappears in the uterus during pregnancy as a result of miscarriage of one twin or multiple. The fetal tissue is absorbed by the other twin, multiple, placenta, or the mother."
A Chimera Can Possess Both Male And Female Sex Organs
If a female twin absorbs her male twin in the womb, or vice-versa, the resulting chimera can possess both sets of genitalia. In one case, a woman conceived by in vitro fertilization, implanted three fertilized eggs into her womb. Only one baby was born.
Her son appeared to have normal male genitalia, but surgical exploration would reveal an ovary, a fallopian tube, and part of a uterus in his body. After their removal, he was able to continue to grow with no further female genitalia appearing.