There are human chimera too. A woman once went to court to get child support from her babies' daddy. A dna test was done, and he was found to be the daddy in both cases. But she was not the mother, according to the DNA. Pregnant with their third child, a member of the court was present when she gave birth and a DNA sample was immediately acquired. They found that according to the DNA, she was not that child's mother, either. Further testing discovered that she's a chimera. Genetically, she is her own twin, and it is her twin that is the biological mother of the children.
Lydia Fairchild Is Her Own Twin - Business Insider
(this is the picture in the article)
Makes you wonder how many of those baby daddies on Maury dodged a bullet that way.