Why do we make antibodies to ABO blood groups even without exposure?

[@omarkhattab5573]

Great Episode ! But a theoretical question Come to my mind after watching this episode: Given the fact that we develop ABO Antibodies because of similarities between the ABO carbohydrates and antigens on bacteria, parasites, and in our food, i wonder why wouldn't our bodies make Antibodies against our Own RBCs' Antigens. For example, Why a person with Blood Group A or Blood Group B doesn't develop Anti-A Abs or Anti-B Abs Respectively. I mean that situation wouldn't be compatible with life but i think it's weird that if we are exposed to same food and Environment, People with Group A Antigen would't Develop Anti-A Abs while those with Group B Antigen would develop Anti-A Abs.