Homophobia arises much from religious codes although a homophobic atheist I know probably gets the homophobia passed down from his father, who's father's father was probably a minister, and also from machismo. In porn, all of the women perform bisexual acts even if they list their orientation as straight. Sex is more of a performance for men, viagra promises an erection lasting 4 hours, and how well you perform is paramount in the macho mindset, whereas non-orgasmic women are accepted.