My son couldn't tolerate breast milk, enfamil, or soy milk. He 's on neocate which runs us about $500 dollars a month. Yes, there is a high crossreactive rate of babies allergic to milk and soy. I guess their protein structure is very similar. At least that is how it was explained to me. I've also heard that babies who don't have gammoglobulin (spelling??) are and can be allergic to breastmilk, even though doctor's tell you that it's impossible to be allergic to breast milk. Just my two cents worth. Elaine mommy to Caleb 17 months...allergic to everything and still on formula.