How likely is it to develop an allergy to eggs at age 18 but were ok as a child?

Allergies develop : At any time. Do not know why, but it is seen all the time that one has eaten a food for years or taken medication before, and then develops an allergy to it. How likely? Depends on the person and family history. It is more likely in someone who already has lot off allergies. Less likely in someone without preexisting allergies.