Crohn's disease is most commonly diagnosed between the ages of 15 and 35, with the average age being around 29.5 years. Some people live with a silent form of Crohn's, experiencing no noticeable symptoms, which means the disease can go undetected for years. Others experience mild symptoms that persist and gradually worsen, taking up to five years before a diagnosis is made. This delay in diagnosis is not uncommon, as initial symptoms are often subtle and may be mistaken for other gastrointestinal issues.