You had two family members with GBM? Isn't that rare? Are the doctors asking questions? My sister passed away in April 2014 and I heard that it's extremely rare in one family. What do you think the cause is? I am just curious because maybe it's something environmental or whatever. Please let me know a little about your brother and sister. Favorite foods, jobs, medications, Cell Phone ,(Is it the side that they used their cell on). Anything that you can think of unique but can connect with the two siblings. I am so sorry, I can't imagine going through such a thing twice.