Trapper,
I wouldn't count on them discovering a cancer cure first. Here is a study showing the physical differences in the brain of heterosexual and homosexual sheep. http://www.ohsu.edu/news/2004/030504sheep.html
What does this prove? I wouldn't be so quick to discount the idea that people are pre-disposed to their sexuality. I think most scientists are in agreement with this, although they are still looking for the proof among humans. In reality, the only people who seem to not want to believe it are the hardcore religious cats. I am convinced that the study confirming the idea is just around the corner.