Gina, I continue to keep your BIL in my prayers.
Sometimes I believe God's answer is "I gave you all free will." Free will is what separates us from the rest of the animals. God gave us free will so that we would be free to choose to love Him and not do so because of instinct. Unfortunately that free will can be used poorly as well. When we think of free will, we often think of our own choices. We rarely stop to consider how our choices, our exercise of free will, affects the rest of the world or how others free will choices affect us.
The chemicals we use, the natural resouces we squander, the things we put into our atmosphere and feed to our animals, all are choices made by humans, and all are choices that do more than affect the individual or individuals who made them. Someone gets into a car and drives drunk - that's free will. If that person hits and kills another individual, it's not God's will, it was the free will choice of the person that was drunk. If we did not have free will, this world would be a pretty perfect place. We would all be God's little chess pieces and our love for God would be empty and so would life, because we didn't choose it. Does this make sense at all?
There's a great line in the movie "Bruce Almighty" (A pretty good piece of theological work believe it or not.) God (Morgan Freeman - my favorite actor) tells Jim Carrey when he turns over his God-job to him "As God, there are only two things you can't do. You can't tell anyone who you are, and you can't mess with free will." He wasn't given the ability to make people do things they didn't want to.
So I don't think God caused the aneurysm, nor did your BIL, but something did and maybe it was due to the exercise of free will by someone generations ago that changed a tiny part of the genetic code. Moonshine, gunpowder or his great great great great grandfather married his sister.
(Just for a little levity.)
That's about as good an answer I can come up with when I think "Why God?" I'll just have to wait until we meet face to face to get a direct answer.