My “comeback” was equal levels rude?

I'm afraid I find it hilarious too... this vision of relatives swapping data at every gathering to assert their place in the pecking order:
"What's your postcode?"
"How many A levels, A stars?"
"Average step count?"
"Cholesterol level? Resting heart rate?"
"How many times did you take your driving test?"
"How many carats?"

I think the problem is that asking someone’s BMI is universally regarded as extremely rude, even offensive, whereas a relative asking a young person’s age is not generally considered particularly rude. A complete stranger or work colleague asking this would be out of line.

You’d have been on sturdier ground if you had waited to hear what she said next.

If you do want to make things good in order to get invited again, you could write explaining you meant it as a joke but realise it didn’t land that way. That might not be quite the truth but she might accept it as it’s quite common for people to say something they intend lightheartedly and for other people to take it much more seriously

Lady Astor: You, sir, are drunk!
Winston Churchill: And you, my lady, are ugly. But at least I shall be sober in the morning.

Be more Churchill 😏

Yes truly Oscar Wilde would have been proud of such a witty comeback.....

Do please send an “I’m sorry if you felt my comments offensive” non-apology text

you know what she was saying, she just didn’t like the fact that you called her out.

You sound delightful @Rebes.

Over the top and very rude of you.

Absolutely amazing comeback! really? She could have displayed that by asking why her Aunt wanted to know her age, not by being totally disrespectful, and frankly rude.

Or why she’s so keen to go back to the aunt’s house.

Well, you have my sympathy, @Rebes! Is your BF's ethnicity the same as yours? I was just wondering if you/your BF could pass it off as a cultural misunderstanding, ie let his family think that asking someone's age is incredibly rude in your culture. I'm sure you're right about her reasons for asking you, from what you say, and it would have pissed me off, too.

Interesting that OP hasn't answered the question about how old BF is...

I laughed! 😂

Far too often, people can only dish it out.

As an overweight 58 year old woman, I think unless you are asking a young person, teenage and under, or talking about age specific subjects eg pension, bus passes etc, both age and BMI are on a par as rude questions. Too many people like to dish out insults, veiled or not, but don’t like it back.

I think an older person asking a youngish person about their age is fine, especially one who may (in their mind) end up marrying into the family.

Maybe she, and the wider family, value women as breeding stock, so that's why it was was relevant to her, but deal with that, don't fling about insults that will have just 'proved' you're an unsuitable prospect for her nephew irrespective of her age.

As OP is apparently in such good condition and is often asked for ID, perhaps aunt was looking out for her, wondering if nephew was pursuing a minor, or some other big age gap!

I think it would have been better to have asked her to tell you her age first.

I don't know what part of the Mediterranean your family is from, but I can attest to the fact that if an Italian aunt asks your age, it is to make it clear that you are either "too young" or "too old" depending on the circumstances, and never as a prelude to telling you that you look great.

On the contrary, I think they have seen exactly who you are.

You judge them for their views, you’re allowed to do that. They judge you for yours, they are allowed to do that. They asked you a really normal question to ask someone you are getting to know, you don’t have to answer it if you don’t want. You could have easily deflected it by asking how old they were, then engaging them in conversation about their life. Instead of making a response that made it clear you don’t want to answer it, but in a friendly way, you immediately took offence (based on your judgment) and retorted with something that was hugely offensive in any situation. That is who you are.

You have continued to make excuses for why you did it. I don’t think you regret saying it, you think it was a clever retort and maybe wanted everyone to clap and cheer. You regret the fall out from it. Would you have posted about it if you hadn’t subsequently been banned from her house (which, by the way, is entirely appropriate for her to do). On the one had you say your boyfriend is annoyed, on the other you say he understands. I can’t imagine anyone being happy with their partner offending a family member the first time they met. I expect he is keeping quiet about it to keep the peace.

You mention her saying she thinks having sons is better. This is a debate that often rages here on Mumsnet. I think having a daughter is better than having a son. Because I have one, and I love it, and boy mumming looks like really hard work. My sister watched me having to go through “teenage girl” mumming and was hugely relieved she didn’t have to do that, she loved being a boy mum. Neither of us that that personally.

You have one opportunity to turn it around. You make contact with her directly and apologise profusely, no excuses.

Not funny at all.

My response would have been don’t you know it’s rude to ask a lady her age? No need to be so rude back to her though.

It's bloody hilarious. And it shut the Aunt up

I don't see the aunt's question as rude at all, more just making conversation. I've been asked my age before. I would never see an issue with it and I am now 60.

The OP's response was bizarre, incredibly rude and irrelevant.

People may disagree with me on that if they wish.

I don’t think there’s anything false about their impression OP.

I hear ya. I think the aunt's remark might have been the straw that broke the camel's back. One incident too many, and you crack. Often happens to people pleasers, because even we have our breaking point 😅

To maintain the moral high ground is, if nothing else, tactically smart - but it's so easy to slip in the heat of the moment.

I do think it's a good idea to trust your gut in these situations. If OP knows the family well, she's probably well-equipped to discern what's going on.

So why did you react so strongly to it? You should be proud of everything above, not 'sensitive' to it. There's ways of dealing with niggly people without coming across as an arsehole yourself.

And at least wait for her to actually be rude before you jump in with both feet!

Now you're going to have to fall on your sword and admit to her of all people that you ARE sensitive about being asked your age, just to keep the peace!

There’s a huge difference between asking someone their age and asking their BMI, you had no clue why she was asking she child have been making polite conversation however it would never be appropriate to ask about her BMI, you were very rude.