As you have probably noticed, none of the Lessons offered include talk about Sexual Orientation. The reason for this is that transgenderism, or our gender identity, is a distinctly different issue from our sexual orientations. One is who we are, the other is whom we wish to love. Now, for those that have surgery, it certainly does affect how we experience or express our sexual lives. And it also follows that as humans, we are to be accorded a healthy sexual life just like anyone else. The common misconception though is that this is an odd expression of sexual desires. It is not.
Another issue in talking about sexual orientation for transgenders is that the commonly used labels - straight, gay, lesbian, bisexual - don't really apply. In my own case, I was a birthed male. Growing up and through adulthood, I was attracted to women - the classic definition of "straight". Following my transition and surgery, I remain attracted to women - which would seem to be the classic definition of being "lesbian". Yet my "orientation" has not changed...only my body. I freely accept the label of "lesbian", but I don't feel I've gone from "straight" to "lesbian" simply because of surgery. As such, I will usually portray myself not in today's current words, but to say that I am "oriented toward women".
Transgenders, like everyone else, hold all variety of sexual attractions, which further confuses most people. We are male-to-females (MtF) who like women...who like men...who like both...and who are not sexually active/interested at all! And we are female-to-males (FtM) who like women...who like men...who like both...and who are not sexually active/interested at all! Expert opinion is that our sexual orientation is immutable, and I agree. Which is why it is odd to suggest I was "straight" and now I'm "lesbian". Again, I don't mind having that label, but it does connote the suggestion of a change in orientation. Only my body changed.
Now let me muddy the waters a bit here. In her book "She's Not There" author Jenny Boylan offers a comment from her surgeon that it was his anecdotal observation that some (perhaps as much as a third) post-surgical transgender women do experience a bit of a shift in their orientation. I personally acknowledge that since I transitioned, I see men in a much different light now and could entertain a relationship with the famous Mr. Right. I've never had an interest in men before. I am faithfully married, so this won't happen.
One last comment is about our potential partners. If this was sincerely some sexual pursuit, then the joke is on us. Once one has gender reassignment surgery, the pool of possible partners drops dramatically. Most straight men are not interested in a transwoman because we "used" to be men. Gay men are not interested in a transwoman because we now look female and have female bodies - things that do not attract them. Most straight women are not interested in a transwoman for the same reason as the gay man. And many lesbian women are not interested in a transwoman for the same reason as the straight man. The same situation applies for transmen. As a result, many transgenders are sexually inactive. And many are asexual - for this is not about our sex lives!