Chimerism: The Science of Two DNA Profiles in One Body
You might have heard the word “chimera” (pronounced ky-MEER-ah ) before. In ancient Greek mythology, it was a terrifying monster made from three different animals; part lion, part goat, and part snake. But in modern medicine, a chimera is something far less scary and much more fascinating. It simply refers to a living being that contains two different sets of DNA in its body. If that sounds like science fiction, it’s not. It’s a real biological quirk that can happen naturally in humans. Let’s break down how it happens, why it matters, and why it’s usually nothing to worry about. How Does Someone Become a Chimera? There are two main ways this happens: one natural, and one medical. 1. The Natural Way: The “Vanishing” Twin This is one of the best-known natural ways chimerism can occur. Early in a pregnancy, a mother might be carrying two tiny embryos (twins). For various reasons, one of the embryos stops developing very early on. However, the surviving twin doesn’t “eat” or “destroy” the ...
