While this is controllable to a certain extent, in reality, most people cannot simply move to places where the prevalence of IBD is low.  Unsurprisingly, urban and industrial areas have a higher prevalence than rural and unindustrialized areas.  The further north you live also has a bearing on risk, as IBD prefers colder climates. Those who live in urban areas are also more likely to consume processed foods which does not help.

Read about how people who grew up on livestock farms are less likely to have IBD.