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Like Genes, Our Microbes Pass from Parent to Child

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We all know that our parents pass on heritable traits, including skin color and height, to us through their genes. Now, the Human Microbiome Project - a department of the National Institute of Health - has produced findings to suggest that our microbial genes are also transmitted vertically from our ancestors. Before we explore this exciting discovery, let’s start with some basics:

Things to Know About Microbes

What is a Microbe?

A microbe is a general name that goes for all living things that are so tiny that you need a microscope to see them. Bacteria, viruses, protozoa, and fungi are great examples of microbes.

What do Microbes Do?

In short, everything. The human body is home to thousands of microbes including bacteria and fungi, some of which are harmful while others are helpful in different ways. For instance, fungi help to kill harmful bacteria while the Streptoccocus pyogenes bacterium is known to cause sore throats.

Where are microbes found?

They occur in varying numbers on our skin and in our mouth, stomach, and intestine. Nobody knows precisely how many microbes in the human body, and while for the longest time the belief was that microbes outnumbered human cells 10 to 1 - new research puts the numbers as roughly the same.

How are Microbes Classified?

The microbiota in our bodies can be categorized into four types, namely:

Archaea - Mainly found in the gut and digestive tract. They produce methane which sometimes leads to flatulence or belching. Generally not harmful otherwise.

Bacteria - Found in about every part of the body, from the gut to the mouth to the vaginal cavity and the skin. There are good bacteria and harmful bacteria, known as pathogenic bacteria.

Fungi - Yeast is an example of fungi present in the human body, which is found most commonly in the gut. Fungi are also present in the skin although in lower numbers and can become pathogenic if circumstances allow.

Viruses – Whilst often associated with disease and opportunistic infections, there are also commensal members of our virome. The virome often has immunomodulatory effects.

How do microbes pass from parent to child?

A common belief amongst mothers is that babies are safe from germs and bacteria while they are in the womb and only meet microbes during birth as they pass through the birth canal and when being held. However, a few recent studies suggest that the uterus may not be as sterile as we think it is.

According to scientists, there is a type of microbe found in placentas that, while not being overtly harmful to the mother and baby, is transmitted to the fetus over the pregnancy period. Tests have also shown the presence of microbes in amniotic fluid and even the umbilical cord. In fairness, these microbes have been found to be harmless and are considered part of the baby's microbiome. Such findings have caused debate among the scientific community over whether bacteria are foreign bodies or innate to the human body. Most importantly, where do microbes live in a fetus and how do they survive the womb environment?

When a baby is born, it is covered with the mother’s microbes, especially if the delivery was through the birth canal. Inevitably, it swallows some of these microbes which then go on to become founder members of the internal microbiome.

Additionally, mothers pass microbes to their offspring through breastfeeding and skin to skin interactions. Breast milk contains microorganisms that support the growth of beneficial microbes and alter the development of pathogens and opportunistic organisms.

By the age of three, toddlers have fully developed microbiomes consisting of diverse populations of bacteria, fungi and viruses collected from their immediate environment. In the gut, for example, the infant microbiome will resemble that of an adult at this point.


Microbes are part and parcel of our lives, and no matter how we try, we can never fully eliminate them. And then again, why should we? Most of them have been proven to be beneficial to improving our immunity as well as helping us fight various diseases. We may never get to meet the scientist who discovered microbes but we should be eternally grateful they exist!

About the author: Lucas M. Cappel is a travel enthusiast and an educator in human culture from NYC, US. He is fond of writing articles on various topics. Apart from his main field of activities he also works on his personal project. You can check out reviews on BestTechExpert to learn more about it.