[jsmith45]

But even in ancient Greek culture there was still something akin to homophobia. While err... screwing a guy as a guy was just fine, being screwed by a guy is not. I.E. being the receptive partner as a male was heavily socially stigmatized. It seems this was viewed as being basically being effeminate, and unsurprisingly that was viewed negatively.

It seems to be extremely common over the ages that women acting like men is more accepted than men acting like women. Even during times when women acting like men in some respect was highly taboo, the reverse almost always seems to be viewed as worse. (I.E. back in the days when a woman wearing pants was scandalous, it generally seems like a guy wearing a woman's dress was even more scandalous).

This dislike of men acting like women definitely seems to be one factor in modern homophobia (although it is not the only factor). It also seems to factor a lot into transphobia (which seems to be much more focused on trans women than on trans men). Of course I suspect that transphobia in men is frequently intertwined with homophobia. The idea being the revulsion found in the idea of finding out that the woman you are dating "is really a man" (in the bigot's mind), making them effectively gay.