The gender ratio, the geographic region and the presence of a pet – these are the things that your house dust can reveal about you. In a recent study, researchers surveyed 1,200 homes and found thousands of bacteria and fungi in house dust.

As a result of a growing number of people settling into urban lifestyles, we’re spending a greater amount of time with the microbes found in our house. Some of these microbes could have a negative effect on our health, while others could actually be beneficial. The problem lies with how little we know. To get a better understanding of how microbes can influence human health, researchers collected dust from a spot many of us overlook when cleaning – the top of door frames.

Analysis of the samples revealed more than 125,000 kinds of bacteria and 70,000 types of fungi in total. They found that the average household had more than 2,000 different types of fungi. When comparing indoor and outdoor microbes, researchers found indoor bacteria and fungi to be more diverse than those found outside, because many outdoor species were being brought into households.

The study, which is published in the journal Proceedings of the Royal Society B, was co-authored by Dr Noah Fierer, who told BBC News: “People do not need to worry about microbes in their home. They are all around us, they are on our skin, they're all around our home – and most of these are completely harmless.” 

“It is just a fact of life that we are surrounded by these microbes,” he added.

What was particularly interesting about this study was how indoor microbes were strongly influenced by the people living in the house, the home’s location and whether they had pets. The geographic region heavily influenced the makeup of indoor fungi, as most entered homes through windows and doors.

Whereas the type of bacteria found inside the home varied according to who lived there, particularly depending on the ratio of men to women. Two kinds of skin bacteria, known as Corynebacterium and Dermabacter, were more abundant in homes with more men. Roseburia, a type of bacteria found in human feces, was also more common in homes with more men. Researchers attribute these variances to a number of factors, which include differences in skin biology and hygiene practices between men and women

Pets also influenced household bacteria. Researchers found 56 different types of bacteria that were more abundant in households that owned dogs, and 24 types of bacteria more abundant in the homes of cat owners.

The findings could lead to the development of new techniques for forensic investigations. Researchers are also keen to further investigate how exactly these microbes affect our health. The study saw researchers from University of Colorado collaborate with a citizen science project called The Wild Life of Our Homes.