This sentence is in English. Let's call the previous sentence the example sentence. The example sentence provides very little in the way of meaning. A language, words, sentences, all of these things are used to express meaning. Similarly, there is such a thing as gene expression. Depending on the signaling in the environment, genes express themselves differently.
So, if a condition is considered to be genetic, that is about as helpful as reminding me that this sentence is in English. It conveys some small truth, but in doing so throws a thick blanket over bigger truths. Hemochromatosis is legitimately genetic, more so than things people like to fob off on genetics, like autism. People with hemochromatosis have two copies of genetic mutations and too much iron builds up in their bodies. If they don't figure this out, they die. If they do figure this out, they radically change their behavior in a bid to limit how much iron can build up in their bodies.
So, radically changing behavior with more complicated conditions, which are still attributed largely to genetics, seems to be the sensible thing to do. The problem is, when people say something is genetic, they are usually suggesting that there is no point to trying a different diet or protocol.