The problem lies from my dad who claims to have allergy to animal blood detected by medical studies in England 30 years ago (my mom is carnivorous). The three children also have this allergy, but to different degrees. My older sister confirmed her allergy for 10 years ago in the USA, there were no clear studies of the causes, so stop worrying about that and we are vegetarians.
I have many questions as whether the hereditary transfer possibly is by genetic or epigenetic means. I think that it isn't the allergy to the animal protein because we eat eggs and cheese, there is something in the blood. My sister´s daughter doesn't have that allergy.