Some cells in your body may not be yours

Mar 26

2 min read

Updated: Apr 20

Most of us think of the body as a closed system.

Your cells. Your DNA. One continuous biological identity, start to finish.

It doesn’t quite work that way.

During pregnancy, cells pass back and forth between mother and fetus. This is normal. It happens in both directions, across the placenta, throughout gestation.

Most of those cells disappear.

Some do not.

The body absorbs them without disruption.

Researchers have found that a small number can remain in the body for decades. Not just circulating in the bloodstream, but embedded in tissues like the skin, liver, and even the brain.

This is called microchimerism.

If you were born, you may still carry cells from your mother.

If you’ve ever been pregnant, you may still carry cells from your child.

Pregnant belly with hands forming a heart

And in some cases, it goes a step further.

Cells from an earlier pregnancy can remain in the mother’s body and later be passed to another child. Which means a younger sibling can carry cells that originated in an older one.

Not metaphorically. Physically.

Some of these cells don’t just remain in the body. They appear to respond to injury and take on new roles. Read more.

What those cells are doing is still being worked out.

Some appear to behave like repair cells, moving to injured tissue and taking on characteristics of the cells around them. Others interact with the immune system in ways researchers are still trying to understand. There are also links to certain diseases, though it is not yet clear whether these cells are part of the problem or part of the response.

While much remains unclear, the evidence suggests the body may hold a kind of record, shaped not just by itself, but by others it has been connected to.