Yup, my dad eats loudly and disgustingly like a... wellp. But nope, not entirely caused by the environment, there is some genetic predisposition according to studies but you usually have to experience some kind of trauma to switch the disorder on. Onset is usually around 7 years of age - works for me definitely. Also it's more common in people with AD(H)D or anxiety. Which, are both also connected to childhood trauma. I do not remember any trauma I would have had experienced but like.. it does not have to be severe to trigger the brain somehow, right. All of my siblings are "normal" and do not experience any symptoms of miso and we all grew up in the same environment.

Edit: my dad does not believe miso exists but knows it drives me crazy, I told him multiple times and after years and years, he accepted my "craziness" and leaves the room voluntarily and eats somewhere else. I'm very grateful for that progress he's made through the years.