Sometimes I realise, a few words into a sentence, that what I want to say just can't be said. At least, it could be said, but if I said it the way I meant it, it would so easily be misinterpreted that I'd be in trouble, or, at least, have to do a lot of explaining. The correct thing to do in this situation is not to start saying anything in the first place. Sometimes you can make an attenuated version of the point you were going to make and then get away with it. I just tried and failed this latter strategy. However, I didn't offend anyone, so I'm going to call it a success. Here's how the conversation should have worked.

Her: Oh, I'm a terrible singer.
Me: Well, in that case, we should never have children.
Her: Why?
Me: Because I don't want your tone-deaf genes polluting my offspring's potential musicianship.

If people didn't have feelings, that would have been a great way for it to unravel. However, that wasn't even close to a possible way of playing it. So, there might have been this:

Her: Oh, I'm a terrible singer.
Me: Oh, that makes you a lot less attractive to me, then. I consider ability to sing as important in a relationship. You don't have to be an opera singer, but at least be able to sing without making me want to retch. And our children would have to have a fighting chance of being musical too.

That, at least, doesn't have as immediate a sexual harrassment impact as the "Well, we shouldn't have children", which implies (in my twisted head) that "at least we're going to have sex, right?". However, it still discusses issues of whether someone is attractive, and it also makes an important point on the genetic purity of my unconceived offspring.

Here's what actually happened:

Her: Oh, I'm a terrible singer.
Me: blah blah blah, oh singing is important, blah blah blah, last girlfriend could sing, blah blah blah. Erm... I'm off now.

Bloody censorship!