I think I have an insight on homosexuality and transgenderism ("Oh boy, this should be good," you're thinking - no, no, I'm respectful and support their pursuit of happiness): So, I know this lesbian couple. One female is petite, very feminine, big boobs, quite traditionally attractive. The other partner is a more blocky sort, more male, big, has kind of a beer belly sort of female. She looks like a friend of mine, who's a guy, a former top high school athlete who's let himself go.
I thought - interesting how the petite woman is attracted to a shape that is reminiscent of a male, yet the target of the attraction is a female. I'm guessing there's got to be a pheromone that the petite one is attracted to - one part of her brain likes the male shape and image, but she's "turned on" by the female scent. And I suppose similar holds true for the bigger, more male partner, except she likes both the scent and the image of the female.
Coming back to the thread subject, I don't think a pure hetero male is going to be attracted to a transgender female, because the transgender female (XY chromosome) is not generating the female "scent". It might work for a bi male, but I seriously doubt it could for a pure hetero male.
Homosexuality I think is about a person being attracted to the "scent" of his own gender, first and foremost. Secondarily, what seems to differ is whether they're attracted to the image of the opposite sex represented by their own gender, or whether they're attracted to image of the same sex as well. Two separate channels, scent-attraction and image-attraction.