Etiologic Theories in Inflammatory bowel Disease Mucosal Immune Genetic System Predisposition BD(Immuno-regulatory Defect Environmental Triggers (Lumenal Bacteria, Infection)Etiologic Theories in Inflammatory Bowel Disease Mucosal Immune System (Immuno-regulatory Defect) Environmental Triggers (Lumenal Bacteria, Infection) Genetic Predisposition IBD