This is not meant to be snarky to the person you replied to, but it’s not possible lol

People commonly say they have an “allergy” to foods when it is simply an intolerance (very different than an allergy) or they just felt poorly after eating it a few times (bad meat, unrelated illness, etc). I am a Dietitian and I see this a lot- particularly in folks with sensitive stomachs, IBS, etc. Someone eats dark meat chicken and it upsets their tummy and they say they have an “allergy,” when really it’s an intolerance at best. This person may have trouble digesting higher fat meats. Sometimes people will also have a reaction to something in a marinade or whatever and just associate it with the main component of the dish.

It is not possible to be truly “allergic” to meat from a one part of an animal but not meat from another part as there is no true difference in composition between the two vs something like being allergic to only the skin of a fruit- the skin and fruit are made of different “stuff”. The only ways light and dark meat chicken differ are in fat content and slightly in micronutrient composition.