You carry your mother with you. Not just in memories or mannerisms, but in an extraordinarily literal biological sense. Hidden within your body are cells that originated from your mother during pregnancy, and they may have been there since before you were even born.

This phenomenon is called microchimerism, and scientists are only now beginning to fully understand how profound and far-reaching its implications are.

During pregnancy, a small number of cells from the mother cross the placental barrier and enter the developing foetus. Remarkably, these cells can persist for decades. Research has found maternal cells in the hearts, livers, lungs, bone marrow and even the brains of children and adults, long after birth. Approximately one in every million cells in your body may be of maternal origin.

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The exchange also works in the other direction. Foetal cells travel into the mother in the same way, and can persist in her body for the rest of her life. Scientists have found foetal cells in maternal tissue decades after pregnancy, sometimes helping the mother’s body heal damaged tissue or regulate her immune system.

Recent research published in the journal Advanced Science, representing the first major output of the Microchimerism, Human Health and Evolution Project, has begun mapping how these cells behave and what role they play in health and disease.

The picture is complex. Microchimeric cells have been linked to healing, immune regulation and tissue repair. But they have also been associated with autoimmune conditions such as scleroderma and rheumatoid arthritis, and may play a role in some cancers. One particularly striking finding from 2024 showed that foetal cells are capable of crossing the blood-brain barrier and becoming functional neurons.

What is becoming clear is that the boundary between one person and another is far more porous than biology textbooks have traditionally suggested. The family you came from may be written into you at a cellular level you cannot see or feel.

Written by

Elle Diaz

Elle Diaz is a freelance journalist and fitness model based in the UK. With a background in health, wellness, and popular culture, she covers the stories people are actually talking about — from viral trends and celebrity news to science, lifestyle, and human interest. Elle brings a sharp, relatable voice to every piece she writes.

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