DEAR MISS MANNERS: I am a young man in my 20s, and I am currently attending university and working as a teaching assistant while I get my master's degree.

I am very small-framed and soft-spoken, and appearance-wise, I look to be about 16. As a result, when I am on campus or in an adult-dominated environment, I am often mistaken for a woman, even though I dress and behave like a fairly typical male.

When students and classmates refer to me as a woman, and I inform them that I am male, I am sometimes met with, "I know someone who has gone through the sex-change surgery, too." Or they ask me, "Are you having surgery to construct a penis?"

My friends have told me to respond with "It's none of your business," but I feel like this implies that I am in fact having a surgery to change sex, and it would stir rumors.

I completely accept people who do undergo sex reassignment, but I believe it is rude for others to make assumptions about another person's circumstances.

Some friends encourage me to be hostile. I do not want to be hostile to my students, and I know that they are just trying to be open-minded and supportive. How can I politely, but firmly, respond to questions and assumptions like these?

GENTLE READER: Being the instructor has some advantages, one of them being the ability to instruct others without being thought rude.

Your assumption that they mean well is gracious and perhaps correct. But if those trying to advance the cause of gender tolerance can agree on nothing else, they generally acknowledge that one of the things they are fighting to overcome is people making incorrect and unwelcome assumptions.

"If you are interested in the gender identity question," you can answer, "this is a really good lesson. I was born, and live as, male. It is dangerous to make an incorrect assumption based on appearance."

This may change their behavior in the future. And it will give you a brief respite while they absorb the news, which, if you do not want a longer conversation on the subject, is a good time to slip away.

DEAR MISS MANNERS: In the past few years, I have received invitations to various events stating the dress should be "California casual," "European casual" or my personal favorite, "smart casual"!

Judging from the wide variations in the way that people have dressed at these events, I am guessing that I am not alone in my confusion. Would you be so kind as to define these terms?

GENTLE READER: Your hosts would likely say the word or words added to a more-or-less well-understood term are there to inspire your imagination. What they likely mean is that there should be a conversation starter to justify your choice.

Miss Manners thinks they are a waste of time and ink. Casual is casual. Consider yourself fortunate that none of your hosts' additions are contradictory, as in "business casual." Although she would not recommend issuing it as an instruction, she has seen ensembles that can only be described -- and not in a complimentary way -- as “casual formal.”

(Please send your questions to Miss Manners at her website, www.missmanners.com; to her email, dearmissmanners@gmail.com; or through postal mail to Miss Manners, Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO 64106.)

DEAR MISS MANNERS: My in-laws spent a week at our home, and when they were leaving, they gave us a thank-you card with a very thoughtful message, but which also included a $200 gift card.

My reaction at first was that it was minimizing our hospitality by being excessive. But then, after declining the gift card twice, I realized that it was a gift from their heart, and I should accept it as they had also accepted my hospitality.

Giving and receiving are two sides of the same coin -- if given from the heart. Aren’t they?

GENTLE READER: Yes, if you are sure that is so. As you believe in your in-laws’ good will, and have read their kind message, Miss Manners will take your word for their warm intentions.

But she knows why you hesitated to accept. Had they given you an actual present of any kind, you would have shown immediate gratitude. Their awkward gesture of handing you the equivalent of money as they left, as if paying a hotel bill, could seem cold and even insulting.

But motivation counts, and you know they meant well, so you were right first to protest, but then to accept in the spirit in which it was intended.

DEAR MISS MANNERS: My good silver set does not include a place setting for dessert. A dessert fork and spoon were never made for it.

I wonder, for a meal including a salad course and dessert, how is this problem to be solved? The salad fork cannot be placed above the plate with a place spoon, as it is needed for the salad course. The dinner fork, of course, has its function.

I realize some may consider this an arcane and asinine dilemma, but it has been bothering me for a good while now.

GENTLE READER: Now, now, that is perfectly understandable -- at least to Miss Manners.

Luckily for you, dessert services are not required to match the rest of the flatware used for a dinner. Also in your favor, although sad: Silver is in declining use, so you should be able to pick up a vintage dessert service cheaply online.

DEAR MISS MANNERS: My wife is part of a large group of friends, and lately, when this group throws a party, the person organizing the party includes a request that attendees wear a specific color.

If you are a participant in a wedding, I understand the desire that folks be attired in matching colors, but now these ladies in the group are telling guests they have to wear clothes of a specific color. Is this some new requirement that I have not heard of, or are these requests getting out of line?

GENTLE READER: While this sounds as silly to Miss Manners as it does to you, she notes that neither of us is a member of this group. If your wife and her friends want to maintain wardrobes in multiple colors to attend occasional little costume parties, it is not our business to interfere. And if it is your wife who objects, she should open a discussion with the group.

(Please send your questions to Miss Manners at her website, www.missmanners.com; to her email, dearmissmanners@gmail.com; or through postal mail to Miss Manners, Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO 64106.)

DEAR MISS MANNERS: What do you think of the so-called Billy Graham rule, practiced by the vice president and some other politicians, where a man refuses ever to be alone with a woman who is not his wife?

Isn’t that exactly what etiquette has always preached, in its rules about the necessity of chaperones and its shaming of women who were told that they deserve what they get if they go to a man’s apartment?

GENTLE READER: What do lawyers and judges think of laws that upheld human atrocities, even including slavery?

Etiquette, like the law, is tradition-based. But when there is good reason to change, both law and etiquette authorize change -- if sometimes centuries after horrendous damage has been done.

Note the word “authorize.” This process is not license for people to go about discarding obligations they do not like. You did well to check with the highest authority.

In the matter of chaperonage, etiquette finally came to realize how vulgar it was to assume that given the opportunity, any man and any woman must be engaging in only one activity. So, a century ago, Miss Manners’ distinguished predecessors abolished the rule requiring social chaperones for respectable young people. That they were not following it anyway may have had something to do with this leniency.

It had always struck Miss Manners as strange that lingering forms of protectionism have restricted the lady, rather than the assumed predator. She recalls making this point in regard to the women’s dormitory curfew rules of her school days. (Nobody listened, but 10 years later, another student -- a future politician -- successfully canceled the curfew.)

A paramount consideration now is the devastating effect that such appendages would have on female careers. And in the cases you mention, it is the males who are calling for supervision. Perhaps they have the decency to realize that they cannot trust themselves to behave professionally. In that case, they should, indeed, provide chaperones to keep themselves in line.

DEAR MISS MANNERS: A good friend of mine, who is having a baby, received a gift today off her baby registry. However, it's from a person she doesn't know.

We looked, and there is another woman with a baby registry with the same name as my friend, but my friend's name populates first in the list. We think this person may have purchased from my friend's list accidentally.

But now she isn't sure how to play this. Does she contact the stranger and thank them? Contact them to see if they made a mistake? What would you recommend?

GENTLE READER: Could it be any clearer that this was a mistake? Strangers do not look up registries in order to send presents to unknown recipients.

That you have the least doubt about this worries Miss Manners. Your friend should immediately contact the store, which will contact the buyer. If she is then informed that, indeed, it was a random gesture to a stranger, Miss Manners will apologize for suspecting you both. If your friend is hesitating, you might point out that the other expectant mother may be receiving her presents.

(Please send your questions to Miss Manners at her website, www.missmanners.com; to her email, dearmissmanners@gmail.com; or through postal mail to Miss Manners, Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO 64106.)