Is avoiding foods that are likely to give my kid an allergic reaction as early as she’s a baby will guarantee her that she won’t be allergic to them when she gets old?

Children who are at high risk of developing allergies, like those whose parents or siblings have allergies might benefit from being introduced to solid foods known to cause allergies, at a later period. It's best to offer least-allergenic foods, such as rice cereal and root vegetables, first. When you introduce grains, save wheat for last, as it's the most allergy causing grain. While egg yolks are okay to try, egg whites are a source of the allergenic protein, albumin, and should be reserved until your baby's a year old, has been exposed to more solids and his immune system is more developed. Source: http://www.parents.com/baby/health/allergy/introducing-solids-to-prevent-allergies/