Irritable bowel syndrome (IBS) is the term for inflammatory conditions that affect the intestinal tract. There is little evidence showing that the condition runs in families.

While inflammatory bowel disease (IBD) has genetic ties, research cannot find a strong genetic cause of IBS. Studies indicate that lifestyle factors play a larger role in whether a person will develop the condition.

Some factors that may contribute to IBS development include experiencing intestinal infections, mental health conditions, and early life stresses. Although there is no way to avoid IBS, some prevention strategies may involve incorporating polyphenol-rich foods and beverages into the diet. Polyphenols are compounds with antioxidant and anti-inflammatory properties.

Keep reading to learn more about genetic links in IBS, as well as risk factors, means of prevention, and when to contact a doctor.

A mother and daughter cooking together.Share on Pinterest
golero/Getty Images

Research from 2016 reviewed studies exploring the genetic risk of developing IBS and found the condition may stem from polygenes with certain genetic variants. Polygenes are genes with individual effects too small to make a noticeable difference, but that can produce a noticeable variation in combination with others.

In some cases, the genetic risk stems from a rare single-gene mutation. However, in most cases, the risk is due to polygenes.

Researchers have identified very few IBS-risk genes. One exception is an inflammation-promoting gene called TNFSF15.

Learn more about IBS and its potential causes.

Epigenetic risk

A 2020 review explains that in addition to genetics, there is an epigenetic aspect to the risk of developing IBS.

While genetics denotes the DNA sequence on a chromosome, epigenetics refers to how environmental and behavioral factors affect genes. Epigenetic factors affect the expression of a gene, which means they can turn a gene on or off.

For example, early childhood stress is an environmental factor that can cause epigenetic changes.

Doctors classify IBS as a functional gastrointestinal disorder. This means its symptoms are not due to structural or biochemical abnormalities.

Instead, there is an issue with how the brain and gut work together.

Despite this, certain factors occur more frequently in people with IBS and may contribute to the condition. These include:

An older study from 2014 found that the risk of IBS is higher among first, second, and third degree relatives, which may suggest a genetic influence.

However, the results indicated that spouses of people with IBS also have a higher likelihood of having the condition, suggesting that nongenetic factors may play a role as well.

Researchers classify relatives as follows:

  • First degree: Parents, children, and full brothers and sisters.
  • Second degree: Uncles, aunts, grandparents, grandchildren, nephews, nieces, and half brothers and sisters.
  • Third degree: First cousins, great-uncles and great-aunts, great-grandparents, and great-grandchildren.

Older research from 2008 indicates that the familial relationship to IBS is stronger in parents and siblings than in offspring. It also suggests a slightly more robust relationship between mothers and sisters.

A 2010 study provides some quantification about the strength of family influence. It indicates that people who have relatives with IBS may be 2–3 times more likely to develop the condition. Unlike the 2013 investigation, this study did not suggest that spouses of those with IBS have a higher risk.

The authors noted that while the family association is clear, researchers do not know how much stems from genetics and how much is due to shared household environmental exposure.

There is a range of risk factors for IBS, including infectious enteritis. This infection causes inflammation in the intestines and usually stems from consuming food or beverages contaminated with a disease-causing microorganism.

A 2017 review investigating IBS risk factors using data from 45 studies involving 21,421 individuals suggests that those with infectious enteritis may be 4 times more likely to develop IBS than those without the condition.

It also found that more than 10% of people with infectious enteritis later developed IBS.

According to the review, other risk factors for IBS include:

Research from 2019 reports that prior studies have found polyphenols may help protect against heart disease, cancer, diabetes, and gastrointestinal conditions. These compounds have antioxidant and anti-inflammatory properties.

Because of the earlier findings, the study authors specifically sought greater clarity about the value of polyphenols for IBS. After reviewing scientific data, they concluded that polyphenols might help prevent or reduce IBS symptoms.

Sources of polyphenols include:

A person should contact a doctor if they have symptoms of IBS or a persistent change in bowel habits.

These symptoms include:

More serious symptoms involve:

Although IBS can run in families, no research has found a significant genetic link. Lifestyle factors are more likely to contribute to the condition.

Risk factors include having had intestinal enteritis, especially if a person took antibiotics for the condition. People with symptoms of IBS should contact a doctor.

Visit our dedicated IBS hub for evidence-backed resources on managing the condition.