Natural and artificial flavors


I've been studying natural and artificial flavors and it's a very confusing topic because according to my research natural and artificial flavors have the same chemical make up. Plus both are man made synthetic flavors made by a flavorist. Here's where it gets confusing Green Mountain Coffee has the single serve K cup coffee and they have a hazelnut coffee I called the company and they said that their coffee doesn't have nut allergens it their product,even their flavored coffee's are nut free. From the research I've done when a flavorist makes a flavor of something they use the same chemicals that is in the actual flavor they are mimicking. My mother in law is allergic to berries and she has trouble even if no berries are in it but it has berry flavoring. So is that the same as with nuts if they say it's a hazelnut coffee and if it's flavored with man made synthetic hazelnut flavoring wouldn't you think that a person would also have the same reaction even though there is no actual nut in it? I really do not know if the hazelnut coffee is flavored or just called that because the beans have a nutty taste to them so they just call it hazelnut. My son is so allergic to things that they can't do skin testing for peanuts and nuts or milk because he had an anaphylactic reaction to the skin test. They did a blood test and the severe end of the allergy is .75 to 1.0 and his came back as 30 so we have to check even the smallest of small amounts or traces of nuts or milk. His allergist wrote an article in a magazine about my sons allergies because he said he never has he seen anyone so allergic to something. Anyone know about flavorings?