Ying posed the following scenario/question: "Recently, I heard a lesbian woman comment about a trans woman (who happens to be a lesbian). She said the transwoman was not "really" a lesbian like she was. It was upsetting to me. No one can define another person's identity, right? It seemed so petty, too. What skin is it off her nose anyway? What are your thoughts on people not accepting a trans person's sexual orientation as being valid?"
Something to consider is going into this is that even though many of the LGB portion of our acronym are supportive and allies, that makes them no less cisgender. Just like any non-LGB person, they're acting from a position of cis privilege, and don't understand the implications of their actions, because, frankly, they don't have to think about it much. We pop up once in a while, in a single circumstance here or there, and that's generally the extent of it. And while they're our allies for political purposes, I've come to find in my experience that LGB people are often woefully ignorant of the issues of the transgender community they support. Which is no surprise, really: We're a vastly smaller group, a minority within our lgbt minority, so appropriately less time is spent on issues relating to us. (Just a shout-out to the LGBTU student group at The University of Akron, as they break this trend and give trans issues a much larger chunk of the spotlight than we deserve by population, because they've recognized the importance of these topics. Well done on them)
So what does this mean for the lesbian in question? Well, she's invalidating our trans lesbian's identity, plain and simple. By saying she's not 'really' a lesbian, she's implying an awful lot, and none of it is good. First and foremost, let's go ahead and define "Lesbian": a lesbian is a woman* who is attracted exclusively to other women*. Pretty simple definition, right? Well the two key elements are "Woman" and "Attracted exclusively to other women". By saying she's 'not really a lesbian' she has to be excluding our trans lesbian from one of the two criteria: and since, presumably, the trans lesbian has been with, or is currently with another woman, and has shown no interest in men, we can assume that 'Attracted to other women' is true. This means the only remaining conflict is in fact, our trans lesbian's womanhood. There's no other way around it.
Nobody else can define you but you. Labels are tools that you apply to yourself, and are not end all be all, but if the trans lesbian identified as trans lesbian, then she's a trans lesbian. It's not particularly up for debate.
As far as her actions, not petty so much as it's cissexist. It's a person, in their seat of privileged power, defining someone of a marginalized minority, which of course they feel free to do, because we're clearly not better informed of our own identities than they are. And yes, people may point out that "We're all LGBT here, I'm not discriminating" but the fact is, even though you're a part of the marginalized "L G or B" subgroup, transpeople are a step even lower on the ladder. And the trait that makes marginalized is one that you do not share with us. We are trans, you are cis. You have cis privilege.
The metaphorical 'skin off her nose' is she'd have to think about trans women more critically, and actually admit that they deserve their right to womanhood as well as the right to their own autonomy - particularly regarding their identity. This is admitting that she can no longer pick and choose how to define a trans woman as she sees fit. This is a problem because for most LGB people, they're completely fine with trans people, up to the point where it becomes a matter of sexual orientation (I.E. Something they define themselves with and take very seriously), and more specifically, their sexual orientation. It's not petty, no, it's lazy.
Just a thought exercise, for any LGB folk reading this. If a Trans* person, compatible with your sexuality(I.E. Trans man if you're gay, trans woman if you're lesbian) wanted to date you, would you say yes? I'm guessing most of you knee-jerked and said 'no'. Examine why, ask yourself why, and realize that there's a good chance you're invalidating their identity of trans people implicitly by saying so. Even if you help them politically in debates, stand up for them from bullies, it's telling of what you *really* think if it hits close to home and you say "ew, no". Chew on that for a bit, maybe you'll come to some realizations.
And before the inevitable genital argument arises, is that really what you look for in a partner? Is it really the genitals? I've never ever heard someone say "that's a mighty sexy penis you've got there" Or "My what a lovely vagina you have" It's ludicrous. To imply that it's completely irrelevant would be untrue, but to claim that you're utterly unwilling because of this fact is... well, depressing. What if, for instance, a gay cis male came to date a gay cis male, and the latter was found to have been victim of a botched circumcision. Would you instantly dump him because he doesn't have the coveted penis? It's not to say sex is unimportant, but there's more than one way to skin a cat.
I'm going to go ahead and go out on a limb, because I think this is a general issue that plagues the thought processes of people who are trans, as well as people who don't understand trans lesbians, by clarifying once again the basic concept: Sexual Orientation and Gender are INDEPENDENT from each other. People have this fallback expectation that it's a definitive aspect of a woman that she be attracted to men. People further have a definitive aspect of a man that they are attracted to women. (This is heterosexual privilege but go with me here) Basically, since people believe these binaries are the 'normal' baseline, they expect someone who's 'just trans' to be following said baseline. I.E. if you want to be woman, a part of it MUST be that you're attracted to men. (This is also because people falsely try to rationalize why a guy would want a gender change and instantly assume it's sexually motivated). This is what leads people to say such ignorant things as "Well, if you're into guys, can't you just be gay instead?" or this gem: "If you like women, what's the big deal? You're a guy just like anyone else!"
These dismiss the fact that it's not their sexual attraction that bothers them, it's their gender, their body, their social role, etc. You aren't a 'more legit' trans woman if you're into guys, you're a straight trans woman (this argument is commonly framed "Trannier than thou"). Likewise, people shouldn't come to expect that being a transwoman comes with the baggage that you must like men. Likewise likewise, people should absolutely NOT be using a transgender lesbian's sexual orientation as some sort of 'proof' that she must be a guy. This is equating "wants to screw women" with "is a man". It reinforces the notion that being male is screw women ( and actually is homophobic - as any gay man will tell you, they are very much men, and are very much into other men).
A corollary of this is gender presentation. In my own case, for instance, I don't dress super fem - I wear a v-neck t-shirt and pants most days. That doesn't make me any less of a woman, and it would be just as wrong to imply that I'm not a woman because of my manner of dress. (Passing while wearing less feminine clothes is a whole other story, but the principle is still relevant).
Something to consider as a litmus test in this sort of situation is to ask yourself: If the person were cisgender, would I be scrutinizing X aspect of their person so harshly? In the case of the original scenario, were the trans lesbian a cis lesbian, her sexuality would have never been called into question. It's discriminating against a trans person because they're trans. This applies to anything. Telling a trans person "Well why don't you wear makeup? real women wear makeup" is silly, because if she were cisgender, you'd never suggest that she were not a real woman (though you might politely express that she'd look better with it).
That doesn't mean you shouldn't help your trans friend with some social norms they may not be accustomed to, but please try to not come of as patronizing or cissexist (I.E. I'm a real girl, here let me teach you). Many of us who're just beginning hormones are experiencing a second puberty - and much like the first, it comes with awkwardness, confusion, and learning what's expected of you. Understanding that they ARE women, just, in terms of social constructs, inexperienced women, is key. (In that way, its more like teaching your 13 year old cousin than a 'guy becoming a girl')
Basically at the end of the day, cisgender people are conveniently overlooking sexual orientation as being fluid for the sake of using it as proof that they don't have to consider someone's gender identity. It's heteronormative, and just as insulting to homosexuals as it despicable that it's being weaponized against transgender people.
The only alternative to the above is if she mentally created a third category for trans women, but that's incorrect. Trans women are women who are trans. They're not a third category.
Quote of the day: "Searching for the answer's a lonely quest, but the act is liable to bring out your best" Bad Religion, Someone to Believe
(As always, if you have any questions you would like me to address, please put them in the comments section. It is a seriously big help to me, and you get your question examined by me!)
@ Orangeban: Your question has been answered by someone else already, and I don't much feel I have anything I could add to the discussion. You can find a link to their article in the comments section of the "How to be a Trans Ally" post.