Here is an interesting example of the complexity:
"Akilah and Santana tell me that, prior to coming out as trans, they both dated men— but they now have opened up to a much more diverse range of sexual partners. (For their part, Nasash and M Samira currently identify as lesbians.) As they tell it, transitioning expanded their ideas around sexuality and sexual partners."
"It’s a common joke among trans fem people that HRT turns you into what Akilah calls “a transbian.” In a recent article for Broadly, two trans women talked about how they became lesbians after dating men pre-transition; their experiences are echoed in a 2014 study also referenced in the piece."
"Seriously, I used to be a rake-thin, femme, fag bottom, and now I'm a curvy, andro dyke, mostly top," she told Broadly. "What the fuck?""
"At the time, she just saw herself as a particularly femme gay guy; though she was undoubtedly attracted to men, she had difficulty relating to them. "I found guys hot, but I also found a lot of them repellant in terms of personality or maturity," "
"Alison isn't entirely sure why her sexual orientation changed after she began living according to her true gender identity. "I was in a different gender position," she said. Because she didn't identify as male anymore, she suggested, she could "conceive of women as possible romantic or sexual interests" without having to stomach her "disgust at male heterosexuality" or having to view herself as complicit in it. She also noted that having sex with men before her transition made her feel more feminine: "With men, I could be smaller and feminine and be fucked, which I didn't conceive as possible with women." After she started living as a woman, that was no longer an issue for her."
"But there could be a cultural or psychological explanation as well, Dr. Bockting was quick to note. "Another possibility is that once a person challenges prevailing social norms about gender and sexuality, this person feels more free to explore sexual orientation in addition to having explored gender identity," he explained. "In other words, all of us fall somewhere on the spectrum of sexual orientation, but many of us may not explore a certain level of same-gender sexual attraction because this continues to be socially stigmatized.""
"A 2014 study, which surveyed 115 trans people who visited the endocrine outpatient clinic at the Max Planck Institute of Psychiatry in Munich, found that "self-reported change in sexual orientation is quite common" in both male-to-female and female-to-male trans people. Of the 70 trans women in the study group, 32.9 percent said they'd experienced a change in their sexual orientation during their lifetime; of the 18 male-to-female subjects who started out exclusively attracted to men, two said their orientation had switched to being attracted to women only, and one said she had become bisexual"
"Ann's story, as she tells it, is less about strict changes in sexual attraction and more about the loosening of sexual preferences that once seemed fixed and inalterable. She still finds men attractive, and is even dating a man right now, but she no longer holds herself to fixed ideas about what her sexuality is or how it should be defined. In fact, Ann feels that after transitioning, it became easier for her to "open up" romantically and "to love.""