Okay, I went away, slept on this, thought about it for a little while, and decided to make another post (despite bowing out last night). While I gave reasons (physical ones) for not wanting to date trans women yesterday and tried to be honest and fair while doing so, many people including Mumei told me to look behind my sexual preferences. I don't think one has to do that in order to justify their sexuality or what they like, but it certainly doesn't hurt, and it could further the conversation and my own understanding of myself. So I went and thought about it, and I came up with something. Again, I think a lot of people won't like this, but it's just as an honest thought, particularly as an answer to Mumei's question of why the idea that someone who've been attracted to or slept with is trans would put you off continuing to date her, and how this could possibly not be considered pure prejudice. That was an interesting question that I feel goes to the heart of the debate.
So a genuine TRIGGER WARNING - discussion of the physical nature of trans people's bodies follows in a way that might upset an intersex person or trans person, (which is NOT what I want), or could be read as denying gender identity or the physical effects of SRS etc.
Anyway, as a heterosexual man I am attracted to females. Gynephillic, as someone said yesterday. I like the female form and female genitals, and the thought of putting my penis into a female until I ejaculate. That's all pretty standard. Something I didn't touch on yesterday, though, and I also feel is important in this conversation, is my sexual reaction to men. By which I mean, I genuinely believe that an aversion to men sexually is a normal part of my heterosexuality. Now, day-to-day, I do not think about other men sexually (whether they're gay or not, makes no difference), but when forced to (say, confronted with pornographic imagery) my reaction is extremely strong and extremely negative. It is the opposite of arousal. My instinct says 'that's not for you, buddy, and never will be, and that "tastes really bad" to your eyes', while my rational, educated brain might say, 'it's just a naked guy, naked guys and gay sex are both normal, deal with it'. It's only at that lower, baser sexual attraction 'level' that I'm repulsed, but I can't deny that I am, and I feel like that's a part of my sexuality. In particular the thought of contact with another man's penis, especially sexual contact is unpleasant to me, while the thought of being penetrated (by anything, really) is actually quite frightening and unpleasant and makes me sweat just sitting here thinking about it. I'm in my 30s and these preferences have remained unchanged since puberty. It's vanilla, but it's who I am and I'm perfectly content with myself in this regard.
I don't feel like any of this was learned, or taught to me, I feel like these thoughts or instincts arose at exactly the same time as my attraction to females did. Now to address the obvious issue that arises from what I just said, I think that a lot of homophobia and horrible violence in history has arisen from this instinct, which is horrible and which I feel shame as a straight man about, but I don't think that the instinct itself to be specifically unattracted to your own sex is homophobic, and this isn't the post to discuss homophobia anyway (though I'd be happy to talk about that). I certainly learned quickly that my own sexual revulsion towards the naked male body in sexual situations should not in any way colour my opinions of those bisexual and gay people who felt otherwise, and everything was good. (This process took me three years between the age of 11 and 14.)
To sum up that point - Sexuality for me isn't like a magnet attracting me to women, it's like two magnets - one pushing me away from men and one pushing me towards women. Both are extremely strong, though I only ever really consider one of them, as I'm never in situations where I see men in a sexualized context. I'd wager most heterosexual men would, if forced, admit the same sexual instincts.
But this brings us to trans people. In the situation where I'm happily sleeping with a trans woman and find out she's trans, all of a sudden, as much as I wish it wasn't the case, the knowledge that her body developed as male suddenly brings my aversion to the male body into play mentally. I can't ignore or pretend that these thoughts wouldn't occur. I can't ignore or pretend that the thought that I was touching the skin of a former penis with my own wouldn't upset me or turn me off, that the bone structure of the person I was sleeping with was intrinsically male or associated thoughts - all of this would, I believe (and this is hypothetical) be too much for me to want to continue a sexual relationship. It's not a case of actively wanting to deny the gender identity of the person I'm with, it's a case of knowing something about their body that would colour my entire sexual experience with them. As horrible as it sounds, I'd be looking at the shape of her hips or shoulders for any signs of masculinity (even if I couldn't find one!), as my brain fights between the thought of the male physiology (and my revulsion to it) that I know is still there in parts, and the female appearance and sexual experience that I was originally attracted to. (Of course, if it was a trans woman with a penis that would just be out of the question for obvious reasons, but I'm talking about a superficially indistinguishable woman.)
Does this make any sense to anyone? I don't know, but I know it's how I feel. Is it fair on trans people? No, it's not, and I'm sure it's hurtful. I can't imagine how much, as I've never faced those issues. But I was asked to really, honestly look behind my preferences and try and divine my reasons and in interests of honesty and further discussion there they are. I know it will read as the textbook definition of cissexism to many, and I apologise for that and any offence caused.