It is evident that our physical traits are a direct legacy of our lineage. But what about what cannot be seen? Do we also inherit the trillions of bacteria living in our gut?
If you have ever wondered why everyone in your house seems to have a "delicate stomach" or why you share certain digestive tendencies with your grandparents, the answer is fascinating: yes, there is microbial inheritance, but it does not work exactly like the colour of your eyes.
Vertical transmission
The first contact with your bacterial heritage occurs at the moment of birth. In science, this is known as vertical transmission.
During birth (especially if vaginal) and through breastfeeding, the mother transfers an initial "seed" of bacteria to the baby. In fact, recent studies suggest that specific bacterial strains from your mother can persist in your gut for years, acting as an invisible family signature.
However, this is just the beginning. As you grow, your environment moulds that community. So, where does your genetics come in?
Your DNA marks the playing field
This is where genetics becomes crucial. Imagine your body is a garden. The bacteria are the seeds, but your DNA determines the quality of the soil.
Although you do not inherit a specific bacterium as if it were a gene, you do inherit the "host genetics" from your parents. Your genetic code dictates:
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The structure of your intestinal mucosa.
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The composition of your immune system.
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How you metabolise certain nutrients.
This creates a very selective environment. Your genetics creates an internal "climate" that allows certain bacteria from your heritage to thrive while others do not. That is why, even if two people eat exactly the same thing, their microbiotas will be different: because the playing field they inherited from their ancestors is different.
Why does my whole family have a delicate stomach?
This is one of the most frequent doubts. If your parents and grandparents suffered from heavy digestion, it is very likely that you also have that predisposition. And the cause is a mixture of two factors:
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Shared genetics: Hereditary genetic variants (like those we analyse at tellmeGen) that may predispose to inflammation or food sensitivities.
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Family microbiota: By living together, families share diet, lifestyle and environment, which tends to homogenise the gut flora of all household members.
Knowing that you come from a family with certain digestive characteristics gives you the advantage of being able to take better care of yourself.
Your microbiota is unique, like a fingerprint, but it carries the echo of your family history. You are the result of your parents' genetics and the environment you share with them.
