Is it a genetic deficiency to be allergic to dairy?
I wouldn’t call it a “deficiency,” but you could call it an anomaly, meaning it doesn’t happen all that often. It is usually genetic, as far as I know (but I’m not an allergist or a reproductive genetics expert.) Allergies to dairy in people of European heritage were found to be linked to good genes that provided resistance to certain plagues common in humanity’s past. The people with that gene were more likely to survive certain epidemics, and so that gene — which unfortunately apparently includes a dairy allergy in some forms — became more widespread. 🙂 Same kind of thing with Tey-Sachs Disease, in the “Epidemiology” section here: http://en.wikipedia.org/wiki/Tay-sachs It’s an example of a tragic genetic disease which exists in part because the gene that causes it provided people protection from TB or some other epidemic of the past. Scientists are not unanimous about this, but it’s an
