No I don't think so. I am not hung up about sexuality. I don't find men sexually appealing to me. I don't even care for women with short hair as much as I do women with long hair, I think it is because I find long hair to be a feminine trait and very attractive.
I've see gay porn, I've seen transsexual porn, I've seen bi sexual threesomes, I've personally been involved in a few real life situations that involved multiple people, both men and woman, and I know what gets me worked up and what doesn't.
I started masturbating to fredricks of hollywood catalogs when i was 7 or 8 years old, I would also look for the underwear ads in the sunday paper inserts (full color photos of women in their underwear!) I had access to the same material for men, and it doesn't give the same reaction. The idea and thought of a woman's naked body increases blood flow to some lower extremities, the idea and thought of a man's naked body has what feels to be the opposite sex.
I'd say I'm 90% straight or more.