How can seafoods like lobster, crab and squid cause food allergies?

If you are sensitive. If you are sensitive to the proteins in these foods, your body makes antibodies that recognize them and set off an allergic reaction. Most foods have the potential of causing allergies, but a few are more likely and shellfish are among the 8 most common food allergens.
Seafood. In genetic susceptible individuals these seafood contain proteins that can cause allergies.