Scientists Unlock Secrets Of Ancient Human DNA

Chimeras Can Occur Naturally

Human chimeras are not just the product of bone marrow transplantation. For example, there is a “vanishing twin,” which occurs when one fraternal embryo dies prematurely. The remaining embryo absorbs the twin’s DNA, giving the infant two sets of DNA.

Some pregnant mothers may retain some of their baby’s DNA. This trait, known as microchimerism, affects approximately 63% of women, including those beyond 94 years old. The New York Times describes microchimerism as “very common, if not universal.