Be very careful in assigning a “all” assumption. “Some” or “many” remains a better choice.
For example, there may be a direct link between some cases of infectious mononucleosis (Epstein-Barr virus (EBV)), and Graves’ disease. Likewise, there seems to be a geographical-indifferent genetic component, as well as age window, to several thyroid problems.
That is, relatives who live far apart with significantly different diets can still be more prone to thyroid problems, and young people ages 16-28 are far more prone to Graves’ disease, while later middle aged women are more prone to goiter. I think there is also an age window for thyroid tumors, as well.
I don’t consider this contradictory in that iodine is a very potent anti fungal, anti bacterial, anti viral and can’t stand against iodine if we get it in sufficient doses.