Coeliac ancestors

I've been researching and building my family tree and came across very suspicious deaths. My 2xgreat grandfather died of inflammation of the stomach (after 7 days) at the age of 55. His father my 3x great grandfather died of stomach cancer at the age of 60! I'm sure they had undiagnosed coeliac disease! I'm sure that's where those genes come from. My grandmother from the same line had diabetes type one which also has a connection to the same type of genes.(coeliac disease, diabetes type I and Hashimoto's often occur together, if you have 2 you'll likely get the third) They are all Irish btw. coeliac disease occurs in about 5% of the Irish population. Edit: my father has type I diabetes(same line). I have coeliac disease and Hashimoto's.