What Causes Flatulence? Genetics, Digestion, and Control

Last reviewed: May 12, 2026 Last updated: May 12, 2026

Written by: Jay Hastings , CEO of PlexusDx

Jay Hastings is the CEO of PlexusDx, a precision health company focused on genetic testing, blood biomarker insights, and personalized wellness recommendations. He has more than 20 years of experience across healthcare innovation, genomics, laboratory operations, healthcare investing, and strategic finance. His work has included scaling healthcare startups, leading CLIA lab integrations, and helping expand consumer access to precision health tools.

Medically reviewed by: Jayden Lee, PharmD, EMBA

Jayden Lee, PharmD, EMBA, is the PlexusDx Medical Science Liaison with a PharmD and MBA specializing in pharmacogenomics and clinical product development, with a proven ability to bridge the gap between genomic research and practical patient outcomes. Dr. Lee has more than 10 years of professional experience in clinical pharmacy, academia, and research.

This article is part of the PlexusDx Education Hub — your resource for evidence-based guidance on diet & genetics. Browse all Diet & Genetics education

Everyone passes gas — a healthy digestive system produces it as a normal byproduct of breaking down food. But the amount, frequency, and triggers vary a lot from person to person, and some of that variation is written in your genes. Genetics influences which sugars you can fully digest and the makeup of your gut microbiome, both of which shape how much gas you make. Understanding those pathways can turn a frustrating symptom into something you can reason about.

Where intestinal gas comes from

Flatulence has two main sources: swallowed air and gas produced when gut bacteria ferment undigested carbohydrates in the large intestine. When a food component is not fully absorbed in the small intestine, it reaches the colon, where bacteria break it down and release hydrogen, carbon dioxide, and sometimes methane. The more fermentable material that reaches the colon, the more gas you tend to produce.

LCT and MCM6: the lactose connection

One of the clearest genetic influences on gas is lactase persistence. The LCT gene encodes lactase, the enzyme that digests lactose in dairy. Whether lactase stays active into adulthood is controlled largely by a variant in the neighboring MCM6 gene — rs4988235. People without the persistence variant produce less lactase after childhood, so lactose passes undigested to the colon, where fermentation causes gas, bloating, and discomfort. This is one of the best-understood diet-gene interactions in human biology.

FUT2 and your gut microbiome

FUT2 determines your "secretor status" — whether you secrete certain sugars into your gut lining and other fluids. Non-secretors, who carry two inactive copies, tend to host a measurably different balance of gut bacteria. Because the microbiome is what actually ferments undigested carbohydrates, FUT2 genotype can influence which foods produce more gas for you and how your gut community responds to fiber and prebiotics.

Other genetic and dietary factors

Beyond lactose, some people malabsorb fructose or certain fibers and fermentable carbohydrates known as FODMAPs, and rare variants such as those in ALDOB affect fructose handling. Diet is the dominant lever: beans, onions, garlic, wheat, and cruciferous vegetables are common gas producers because they contain fermentable carbohydrates. How much gas any of these causes depends on your enzymes and your microbiome working together — a genuine gene-and-environment interaction.

How genetics fits into your digestive pathways

The PlexusDx Precision Peptide Genetic Test explores 14 pathways, 49 peptides, 150+ genetic insights, including variants across the nutrition and metabolism pathways that influence how you digest carbohydrates. It offers pathway-level education — for example, whether you carry the lactase-persistence variant — rather than a diagnosis. Genetics is a guide, not a guarantee: it can help explain patterns you notice, but it does not tell you what to eat or diagnose any digestive condition.

Practical ways to control excess gas

If gas is bothersome, a few evidence-based steps help. Keep a simple food-and-symptom diary to spot triggers; eat slowly to swallow less air; and if dairy is a culprit, lactose-free products or lactase enzymes may help. A short, structured low-FODMAP approach guided by a dietitian can identify specific triggers. Persistent or severe symptoms, or gas accompanied by pain, weight loss, or changes in stool, warrant evaluation by a qualified healthcare provider — genetics does not replace that assessment.

Frequently Asked Questions About Genetics and Flatulence

Can genetics really affect how much gas I produce?

Yes. Genes influence which carbohydrates you fully digest and the makeup of your gut microbiome, both of which shape gas production. The lactase gene LCT and its regulator MCM6 (variant rs4988235) determine lactose digestion, while FUT2 affects gut bacteria. Diet, however, remains the largest day-to-day driver of how much gas you make.

What is the main gene behind lactose intolerance?

Lactose digestion is controlled by the LCT gene, which makes lactase, and by a variant in the neighboring MCM6 gene, rs4988235, that decides whether lactase stays active into adulthood. Without the persistence variant, undigested lactose ferments in the colon, producing the gas and bloating typical of lactose intolerance.

Does the Precision Peptide Genetic Test diagnose a digestive disorder?

No. It provides educational, pathway-level insight into how your genes influence carbohydrate digestion and metabolism, such as lactase persistence. It does not diagnose, treat, or manage lactose intolerance, IBS, or any digestive condition. Persistent or concerning symptoms should be evaluated by a qualified healthcare provider who can order appropriate testing.

How can I reduce gas if it runs in my family?

Start with a food-and-symptom diary to identify triggers, eat slowly, and test whether dairy or high-FODMAP foods are involved. Lactase enzymes or lactose-free products help some people. A dietitian-guided approach can pinpoint triggers. Genetics is a guide, not a guarantee, so the habits you control still make a real difference.

Want to see how your genes influence carbohydrate digestion? Take the Precision Peptide Genetic Test.

This article is part of the PlexusDx Education Hub. Browse all Diet & Genetics education

The Precision Peptide Genetic Test analyzes how your genes influence peptide-related biological pathways. It does not recommend, prescribe, or determine which peptides you should use. Consult a qualified healthcare provider before beginning any peptide protocol.

Medical and Editorial Standards

Medical review process: This article was reviewed for medical accuracy, scientific clarity, evidence alignment, and appropriate discussion of genetics, medications, supplements, biomarkers, and health-related claims.

Sources and evidence: PlexusDx educational content is developed using peer-reviewed research, clinical literature, reputable medical references, and, where applicable, public health or regulatory guidance. References are included at the end of the article when scientific, medical, or health-related claims are discussed.

Commercial transparency: PlexusDx offers genetic testing, blood biomarker testing, personalized supplement recommendations, and related precision wellness services. Product mentions are intended to help readers understand available options and should not be interpreted as medical advice.

Important disclaimer: PlexusDx educational content is for informational purposes only and should not be used as a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making decisions about medications, supplements, genetic testing, lab testing, or health-related care.