My brother has recently developed a blood clot in his lung and the dr called it polycythemia. Why now? Why not when he was younger? Is this an auto-immune disorder. Several of his siblings have been experiencing auto-immune disorders such as Celiacs, thyroidism, epilepsy, and now this. Is this a genetic disorder and should I be tested because of my brother. I have already had superficial blood clots in my legs, but no dr has ever research into it, they have just chalked it up to age and bad veins, puting me on a lo-dose of aspirin. I am really worried about my brother and the rest of us....am I just being silly?