I don't think it's hard wired at all, I think everyone is on a large scale from straight to gay (varying degrees etc), and everything in between, and we move up and down on that scale depending on who we meet and what happens to us over the course of our lives, every living moment we slightly shift. I had never even considered the fact I may be into girls until I was asked to go on a date by a friend of mine. So I think anyone would have the possibility of liking the same gender, if they were put in a specific context, but yes there are indeed 100% straight people, no denying that.
This was just my opinion though, not trying to step on any toes
