Hidden Guests: Migrating Cells and How the New Science of Microchimerism Is Redefining Human Identity

A captivating and thought-provoking introduction to the fascinating scientific phenomenon of microchimerism.

In the astonishing process of human development, we grow from a single cell into an entire being, all of our cells derived from that first fertilized egg and containing a unique genetic code. Or so we thought. The recent scientific discovery of microchimerism disproves that widely believed notation, showing us that maybe not all of our cells are our own...

In Hidden Guests, science journalist Lise Barn廩ud explains microchimerism: the presence of genetically distinct cells that originated in another person. Scientists once believed these "hidden guests" to be both rare and harmful, but now know that we are all microchimeric, and that microchimeric cells help regenerate damaged tissues, prevent and treat diseases, and improve the odds of successful transplants and healthy pregnancies.

Weaving fascinating true stories and interviews with experts at the forefront of the research, Hidden Guests traces the history of this still emerging science while asking philosophical and probing questions about the implications of microchimerism to our understanding of immunity, biology, evolution, parental testing, criminal forensics, and the concept of individual identity. Barn廩ud makes the case for expanding our notions of both self and immunity: as ever-changing collectives of cells in relation, we are not unlike ecosystems. And like ecosystems, perhaps, the greater our diversity, the greater our resilience.

Barn廩ud also recounts the surprising and strange cases explained by microchimerism, such as:

• How did a mother give birth to the genetic children of her "sister" who was never born?
• How was a man identified by DNA testing as the culprit of a crime he didn't commit?
• How might you be carrying cells from your relatives or even strangers?