How Living Together Shapes Our Microbiome



We all know our families influence our genetics and traditions. And our closest relationships shape who we are, and they can also change us over time. Like the subtle way your partner may influence your preference for spicy food. Surprisingly, your relationships also shape your microbiome—the bustling community of bacteria, fungi, protozoa, and viruses in your body.

You may have heard that your microbiome is a product of your early life. This is true—a baby's microbiome develops rapidly in their first 1,000 days! Yet, emerging research shows that our microbiome continues to evolve, influenced by our life choices, diet, environment, and significantly—by those we live with. In this post, we'll explore how relationships impact the microbiome.

Mother Jumpstarts the Microbiome

When born vaginally, a baby encounters its first microbes in the birth canal. This process is called microbial seeding, where mom passes some of her vaginal and gut microbes to her baby. These microbes may play a key role in developing the immune system, metabolic regulation, and disease prevention in early life. And disruptions to typical early-life microbial colonization may have long-term implications, like being associated with increased risk of eczema, allergies, asthma, and more.

Studies have found that about half of the bacterial strains in an infant's gut during their first year of life are shared with their mothers. Most of these come from the mother's gut [1-2]. As we grow, our microbiome gets more diverse, and this overlap decreases. It still persists, though, with one study showing that even 30-year-olds may share on average about 14% of strains with their mothers! [2].

Families Sharing the Microbiome

While our gut matures most dramatically before age 3, it continues to shift throughout our lives. Our family members, the living spaces we share, and the meals we enjoy together play a crucial role in shaping our microbiome diversity.

One study found that family members living together have a significant portion of their microbes in common. In other words, family member's microbiomes can look really similar. It's even possible to tell families apart from others living in the same geographic region by their microbes [3]! And another study points out that the longer we live together, the more our microbiomes may have in common [4].

These studies remind us that families are more than just social units; they're also shared microbial environments. Each family's unique mix of genetics, lifestyle, and environment crafts a distinct microbial world. While we are all unique, our family connections run deep, even down to the level of gut bacteria.

Marriage and Microbiome: An Intimate Connection

Close relationships, like marriage, significantly impact our gut microbiota. One study found that couples share about 30% of their microbiome species on average. This percentage was higher the longer the couple had lived together [4].

The evidence for microbiome sharing is even stronger when we look at marital partners. Married people tend to have more diverse and rich microbiomes than people who live alone. Especially married people whose relationships are close. This connection is stronger than any genetic factors or environments shared by siblings [4]. This research aligns with the wealth of evidence linking high-quality relationships to better health and longer life [4-5].

Could the gut microbiome be the reason? Obviously, a quality relationship with your spouse can make you happier. But it's intriguing to think it may also impact your gut health, which in turn, affects your overall well-being.

Relationship Implications for Health and Disease

This microbial exchange raises questions about long-term health impacts in couples. One study found that aspects of relationship functioning, like satisfaction and openness, correlate with gut microbial diversity, beneficial for health [6]. Conversely, holding back thoughts and feelings was linked to lower diversity in this study. 

Let's look further at the quality of our relationships and the microbiome. In one study, individuals with lower marital satisfaction had increased depressive symptoms. They also had a decrease in gut microbial diversity and richness [7]. This suggests a complex, bidirectional relationship between depression and gut health, where gut issues may stem from marital stress. Or, they may precede or even exacerbate depressive symptoms.

It is important to remember that gut microbiome diversity has been linked to many chronic diseases, like diabetes and obesity. It is also linked to chronic inflammation and other health risks. This is evidence that your gut health may be a crucial component of overall well-being.

Gut Health is a Family Affair

Our microbiome is not static, formed solely in infancy. It evolves throughout life, shaped by our social interactions, living arrangements, and choices. As we delve deeper into this microbial dance, we start to see how our daily lives impact our health in previously unexplored ways. Could nurturing our relationships be as vital for our gut health as the food we eat?

When it comes down to it, the only way to truly know what is going on in your microbiome is to test. Whether you’re just curious about your gut or vaginal health or want to get to the root cause of health issues, Tiny Health can help—explore our microbiome tests for the whole family today. 


[1] H. Enav, F. Bäckhed, and R. E. Ley, “The developing infant gut microbiome: A strain-level view,” Cell Host Microbe, vol. 30, no. 5, pp. 627–638, May 2022, doi: 10.1016/j.chom.2022.04.009.

[2] M. Valles-Colomer et al., “The person-to-person transmission landscape of the gut and oral microbiomes,” Nature, vol. 614, no. 7946, pp. 125–135, Feb. 2023, doi: 10.1038/s41586-022-05620-1.

[3] P. D. Schloss, K. D. Iverson, J. F. Petrosino, and S. J. Schloss, “The dynamics of a family’s gut microbiota reveal variations on a theme,” Microbiome, vol. 2, p. 25, Jul. 2014, doi: 10.1186/2049-2618-2-25.

[4] K. A. Dill-McFarland et al., “Close social relationships correlate with human gut microbiota composition,” Sci. Rep., vol. 9, no. 1, p. 703, Jan. 2019, doi: 10.1038/s41598-018-37298-9.

[5] T. F. Robles, R. B. Slatcher, J. M. Trombello, and M. M. McGinn, “Marital quality and health: a meta-analytic review,” Psychol. Bull., vol. 140, no. 1, pp. 140–187, Jan. 2014, doi: 10.1037/a0031859.

[6] Q. Cheng et al., “Relationship Functioning and Gut Microbiota Composition among Older Adult Couples,” Int. J. Environ. Res. Public Health, vol. 20, no. 8, Apr. 2023, doi: 10.3390/ijerph20085435.

[7] J. K. Kiecolt-Glaser et al., “The gut reaction to couples’ relationship troubles: A route to gut dysbiosis through changes in depressive symptoms,” Psychoneuroendocrinology, vol. 125, p. 105132, Mar. 2021, doi: 10.1016/j.psyneuen.2021.105132.