The thing is that there is heaps of discussion in especially FF babies about not having mature enough intestinal systems to deal with processing different foods. BF babies get different proteins etc through breastmilk, but FF babies don't, they get what they are given regularly and their tums aren't developed enough. Often times with allergies things that are given too early can cause problems. Gluten allergy and cows milk protein are probably the worst allergies, but both of those can be found in formulas, so often those allergic babies get picked up earlier than other food allergies anyway. Or are just diagnosed with reflux...