Re: Grey hair turning brown?
Stranger things could happen.
It's a scientific fact that having even one gray hair before the age of 30 means the person is predisposed to having thyroid disease. (A friend found my first one when we were 10!) It's unclear - at least, to me - whether the gray is caused by the thyroid disorder directly, or whether it just a physical sign of a genetic flaw that allows the autoimmune or thyroid disorders when triggered by some outside stimulus.
But thyroid dysfunction can directly affect the hair's texture - making normally straight hair more wiry. And of course, sebum production is affected by hypoT, causing dry, brittle hair. I don't know if I've ever read anyone's account here of gray hair reverting to pigmented. But, I do think it's not impossible. Good for you, if it's so!