IBS is a complex condition with no single cause, but rather multiple factors contributing to its development. One common idea is that it starts in the gut, especially in people with certain genetic factors and an imbalance in their gut bacteria. Factors like infections or certain foods can disrupt the gut's balance, leading to inflammation and immune system changes. This can cause symptoms like gut sensitivity, pain, and changes in bowel habits. Stress and depression can also play a role by affecting gut function and triggering immune responses. 

Dietary factors play a significant role in triggering or exacerbating IBS symptoms. Foods high in fermentable carbohydrates (FODMAPs) and gluten have been identified as potential triggers for symptom flare-ups in susceptible individuals. Elimination diets, such as those excluding high FODMAP foods and gluten, have shown promise in improving symptoms for some patients, highlighting the importance of diet in managing IBS.

Overall, IBS involves a mix of genetic, environmental, and lifestyle factors that interact in different ways for different people.

References: 

Holtmann GJ, Ford AC, Talley NJ. Pathophysiology of irritable bowel syndrome. Lancet Gastroenterol Hepatol. 2016 Oct;1(2):133-146. 

Almansa, Cristina & Houghton, Lesley. (2013). Irritable bowel syndrome: Etiology, pathogenesis and pathophysiology.

"Like a tangled web, diseases often have many threads, with various causes weaving together to create their intricate pattern."