There's a certain amount of run-of-the-mill tact and respect for privacy that starts to vanish when someone comes out as trans*. I'm consistently surprised by the kinds of questions people ask me about my partner, and by the things they say to her or us. One of my favorites is when people tell her how lucky she is that she doesn't have to deal with periods or cramping. I always think, "Yeah, she's really jazzed that she doesn't get to experience fertility and won't ever have the ability to carry a child. How lucky!" I wonder if cisgender women who have had hysterectomies experience the same misguided conversation about their "luck."
A very common experience trans* people have is that conversation can tend to veer rather quickly to their genitalia. While I can certainly understand the curiosity, can we all just agree that conversations about one's genitals are conversations best left under the "personal/private" umbrella? Transitioning doesn't somehow lift that social contract.
Living in the Midwest, I am well schooled in the rose-colored-glasses style of communication that occurs here. You might hear things like, "Oh, that's really different," when someone means, "That is hideous," or, "He's so spirited," when someone means, "Your child is a complete terror." Given that, it's no surprise that I've been asked about my partner's genitals dozens of times and have yet to hear anyone actually use the words "penis" or "vagina." Instead, I hear the same question time and time again: "So... Is she going to do the full transition?" The last three words of that are always emphasized in a wink-wink-nudge-nudge way. Sometimes I address the question head-on; other times I toy with people and pretend I'm unsure what they mean so I can watch them squirm awkwardly. Either way, it always leads to questions about surgery.
Let me be very clear about something: Surgery is absolutely not a requirement for or condition of trans*ness. For some people gender-confirmation surgery is a personal necessity, a life-or-death need. For others it's not. For some the medical risks aren't worth it. For some it's a financial impossibility. And, believe it or not, some trans* people simply don't want any kind of surgery. Each person is different.
When people ask whether she's going to do "the full transition," I most often reply now by saying that she already has. The important thing to remember is that there isn't some kind of finish line. There's not a day in the future when my partner will finally and completely be a woman. She is a woman now. Today. She is not a halfling. She is not transitioning: She has transitioned. Focusing further on the specifics of her genitals is just kind of creepy. Genitals do not make a person. While surgeries can help some people feel more comfortable in their skin, those people were already wholly the gender by which they identified before surgical intervention. Some women have penises. Some men have vaginas. That's that.
With that said, I do understand that it's a topic that comes to mind with immediacy when someone comes out; the notion of transition is very foreign to a lot of people, and focusing on some of the pieces that seem the most curious is one of the ways people begin to wrap their heads around everything. It's an understandable response; however, it can lead to a kind of inappropriate fixation on the "weird" factor, which turns a genuine interest about transition into more of a morbid curiosity. No one wants to be the object of morbid curiosity.
As I mentioned, I've been asked dozens of times about my partner's genitals. How often have you had to answer questions about your partner's crotch? If you and your partner are both cisgender, I'd imagine the answer to that question is "not often." I urge you to hold back the desire to interrogate trans* people or their loved ones about their junk. Not only is the subject private in general, but it can also be a rather distressing topic to someone who experiences gender dysphoria. Above that, it's a matter that's largely irrelevant to one's transition as it relates to people in their lives.
What trans* people have done, might do, or will do in terms of surgery is solely their own business. What's between their legs has no bearing on how they interact with co-workers, family members or friends, so your interest in their transition might best be directed to other areas of it.
If nothing else, be prepared for my response to these questions to be, "Why don't you tell me in great detail about your spouse's genitals first?"