I am a male bisexual. I believe this with a high level of probability, primarily due to my ability to have erections from naked or sexual pictures of both genders. Also the fact that I have felt heavy romantic interest for both genders would seem to indicate that this is very possible.
If you want documented research done into male bisexuality, look into the research of Alfred Kinsey. He researched all forms of sexuality extensively, and was a male bisexual himself.
Edit: Also, the society I have been raised in has practically no instances of homophobia, so I don’t believe that could be a factor.
.… and the Earth is flat, women are inherently less intelligent, spirits bring the rain, mingling blood creates babies, the brain cools the blood, and every other belief once believed by massive segments of the Earth’s population is correct.
.… I would suggest that you start by reading all of http://wiki.lesswrong.com/wiki/How_To_Actually_Change_Your_Mind , and if you already have, then I would suggest that perhaps this website is not for you. Or that you really, really need it. One of the two.