I have come across many stories where a family has more than 1 thal major child. In these families, is the other affected child of the same gender? Do you know of any families with 2 boys major or 2 girls major or 1 boy 1 girl major. Andy, when you said there are some families you have known with 3 majors, are they all the same gender? I'm developing a study to understand this deeply. Your experiences will be invaluable.