My son is transgendered, which is why I stayed here and registered after finding the site by wildly unrelated means. I'll hope that it's also ok for parents to be asking questions. My FTM son is more than a little stereotypical male in terms of talking about his feelings, so perhaps some of you can fill in some blanks for me as I go along here.
The prompting question/comment is the 'can I pass' threads. I understand that this can be a very serious concern for a lot of reasons for people in the trans community, and absolutely don't want to step on anybody's toes or feelings. Keep that in mind if something looks unkind.
My thought, though, which may lead to a suggestion, is that most of the photos I saw in checking through the thread were 'obviously' of the targeted gender. Not really a question (to me, from where I sit, and wearing my shoes of life). If the person was FTM, they looked male, and if MTF, they looked female. No problem. That brought to mind a different comment -- from a transwoman I was talking to at a PFLAG meeting. She was mentioning that she could tell pretty quickly, almost at a glance, who was trans and who wasn't. I don't know if she was really that accurate. But, I can see how one might be, after practice and being concerned about it.
The good news I bear, then, is that in asking the 'can I pass' question in a trans forum is probably asking your most challenging possible audience. Few cis folks are looking very closely.
For a while after my son came out (only a little over a year go) to me, I spent some time looking at people around me to see if I could tell who were the transmen and transwomen. Even in PFLAG meetings where I knew for certainty that some present were trans (say a meeting for parents who were transgendered, which my wife and I went to on grounds of being parents of a transgender child), I would have been hard pressed to get a high score on identifying who was who as to trans or not. Ok, the 6'3+" transwomen I could tell pretty easily. But height is no guarantee, as one of the most striking (cis-)women I've known is 6'1".
And that's another point on what happens even if cis people did look closely. Take my ex-wife, me, and my stepson. My ex-wife is built like a (short) linebacker. Also heavy brow ridges, and heavy bones. I've got very gracile bones, and behaviorially was much more 'feminine' than my ex (meaning that, say, I was more aware of feelings and talked about them, even if far less than, say, my sisters). My son, at this point in transition, on the other hand, looks like a guy and (always did behave so) behaves more stereotypically guy-like than I do. So, of the three of us, the one you're possibly least likely to pick as trans is the one who is.
So my thoughts, I suppose, are:
* You're (the trans community) perhaps the most difficult set of judges as to whether someone 'passes'
* Cis people don't pay much attention, and are pretty lousy judges even if they did
A question is,
* should I be saying much to my son about the fact that he definitely looks, sounds, etc. like a guy?
He definitely does. And I've tried to be good about the pronouns. But I'm also minded of something Caroline (the transwoman I mentioned above) said about one of the best things I could do for/with him was to take him to a bar and have a drink with him. (which I eventually did, at a restaurant/pub/bar in Castro district SF (he's also gay)). That isn't _why_ I was there with him, but, if that was a good thing to do for more reason than just having a place to eat and drink, I'm glad I did.
Similarly, if it's likely something that he'll appreciate -- to hear that he looks like a perfectly ordinary guy* -- then I'd definitely like to be mentioning it. Or, if it's likely to be an annoyance, I'll go ahead with not mentioning it. Since you don't know my son, I'm not expecting perfection in your predictions. But if you can say why it would/wouldn't be good, I can decide how that applies to my son and I'll take my chances.
* Granted that I'm biased, and I think he is a particularly good looking guy. Much better, certainly, than me. But you get the idea.