There have been some studies, I forget where, but they come up with the idea that everyone has a varying level of sexual attraction to the same and opposite sex. Keep the answers coming.
For the record, I'm 'straight' but not 100%. Say like 80-90%, so I'd get an A, har-de-har-har. I only just noticed but I missed out the are in the question, never mind.
Also something some people have pointed out, I don't mean that you'd actively go out and sleep with a member of the same/opposite sex, I just mean there must be some level of attraction.