A woman on TikTok has explained the story of how she found out she is a human chimera, having absorbed her twin sister in the womb.
Rachelle, who goes by the username radrachelle, had always had different colored eyes. As well as this, she had a straight line that goes right down the center of her torso.
"On my left side only, my skin pigmentation is a different color than on my right side," she explained in the video below. At first, she "kind of chalked it up to 'it must be a birthmark'."
However, during her teen years she began to fall ill a lot. She visited a lot of medical professionals, though nobody could figure out what was going wrong. Eventually, she went to a doctor who gave her genetic testing, and she found that she had two DNA profiles.
"He confirmed I am a chimera," she said in the video. "I absorbed my twin sister, so I carry her DNA and cells within my body."
Rachelle has tetragametic chimerism. This happens when two separate eggs are fertilized by two different sperm, and then one of the embryos absorbs the other during the early stages of development. People with this type of chimerism may have two blood types, or different eye colors, as Rachelle does.
Chimerism is rare, with only around 100 documented cases in humans. In some cases of chimerism, the person can develop ambiguous genitalia, if the twin embryos they are developed from contain different chromosomes (i.e. if one twin is male and the other is female). Other people with the condition can live with no complications from it, other than altered pigmentation or eye color.
In fact, some have only become aware of their condition after blood tests. Back in 2006, a mother had to prove her children were her own after a blood test showed that her DNA did not match the DNA of her own children, due to the presence of the DNA of her twin.
In chimeric patients, the majority of cells usually end up coming from one set of DNA, Live Science reports, as is the case with Rachelle. After being asked whether her children would be her own, or from her absorbed twin sister, she responded in a separate video that following the birth of her children she had a hysterectomy. DNA samples were obtained from her uterus and ovaries. Her ovaries were determined to be 100 percent her own, and her uterus nearly the same, with an exception of a few cells.
However, her children are going for genetic testing just to be sure, in case of further health problems that they should know about.