Each person carries a unique germ cloud or germ fingerprint called a "microbiome" that is as unique as DNA.

These germ clouds then settle into homes or wherever an individual goes to, making for even better tracking information than DNA, according to a study published in the journal Science.

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The study consisted of sampling seven families of 18 persons. Out of the seven, three moved during the course of the study. So scientists did tests on two houses and hotel rooms for each of them.

The hands, noses and feet of each member of the family were swabbed, as well as surfaces in their homes.

What researchers found was that it's possible to accurately predict if a person has lived in a certain home and how recently.

Individuals apparently spread their microbiome around. Aside from bacteria, each person's microbiome also contains viruses and yeast that live inside and outside of the body.

"We had a young couple that moved from a hotel into a new house. Their microbiomes overwhelmed the microbiome of the hotel room so their hotel room looked more like their new home, microbially speaking," said Jack Gilbert, an environmental microbiologist at Argonne National Laboratories and the University of Chicago who studied the families,

The occurrence happened within one day.

Gilbert and his colleagues concluded that our germ clouds define who we are and who we spend time with.

Gilbert gave the example of babies that are born practically sterile and quickly acquire the germs of their mothers.

Gilbert said babies acquire their mother's microbiome and this kick starts the child's progression up to about age two. By the time a child turns two, he or she would have developed a "stable unique fingerprint."

Because microbiomes rely heavily on our interactions with others, the microbial diversity of the home affects how disease is transmitted and the immune defense of members of the household. This in essence provides a "road map" to defining the health in the home.

The understanding of microbiomes may also lead to a better comprehension of conditions such as allergies.

Catherine Nagler and colleagues at the University of Chicago observed that mice that have a certain family of bacteria living in the stomach were protected from peanut allergies.

The observation led Gilbert to go back to the so-called "hygiene hypothesis."

According to this hypothesis,  people who have allergies may not have been exposed to enough germs that could have protected them when they were younger. Gilbert believes that having a large variety of germs living in the body protects a body better than a body exposedto one particular bacteria.

Microbiomes also more likely explain how dogs can track people even if they are lost in forested areas.

"Bacteria living on your skin metabolize. They grow on your sweat and they release aromatic compounds from your sweat. Those aromatic compounds are released into the air," Gilbert shared.

Dogs are able to recognize your particular smell, which is emitted by your unique microbiome.

Microbiomes may also help in explaining why some people's homes have unique, peculiar smells.