It has been suggested that gene-environmental interactions (epigenomics) play a role in allergy in early life.
This Japanese study included two pairs of identical and fraternal twins with Food Protein-Induced Gastrointestinal Syndrome (FPIGS).
The identical twins developed vomiting and bloody stool simultaneously.
The fraternal twins developed prolonged vomiting and loose stools at different times.
Their symptoms resolved when formula feeding was stopped, and the symptoms were thought to indicate an allergy to cow's milk. However, the researchers concluded that the most likely diagnosis was FPIGS. Since the symptoms developed at different times, the genetics may play a role.
I am not sure that one can make any firm conclusions from these cases though. It is also worth mentioning that FPIGS is not considered a "true" IgE-mediated allergy.
Food Protein-Induced Gastrointestinal Syndromes in Identical and Fraternal Twins. Shoda T, Isozaki A, Kawano Y. Allergol Int. 2011 Jan 25;60(1).
Image source: Wikipedia, GNU Free Documentation License.
Understanding FPIES Through Moms Sharing Their Stories. Nutricia Neocate blog, 2011.
100% of Greek philosopher named trials showed reduction in mortality, compared with 12% of trials with other acronyms. Lancet, 2011.
International Association for Food Protein Enterocolitis (IAFFPE)
Food protein-induced enterocolitis syndrome (FPIES) - AAAAI Ask the Expert addresses clinical questions, 2012.
@kfatweets: Worse than iPad. RT @Allergy: Wasn't there a better acronym for Food Protein-Induced Gastrointestinal Syndrome (FPIGS)? http://goo.gl/yVwLq
@MatthewBowdish (Matthew Bowdish MD): FPIES is bad enough!