If the Genes fit...

So the Girl has a pre-arranged, pre-paid for, pre-tty much completely organised 'Kerrang' thing happening this coming Friday... by the way... what happened to going to KidsWorld and turning your tongue blue with Slush Puppies and falling off foam-covered rolling logs and laughing til you're sick? - it's true - it DOES go quickly, this childhood thing.  Trust me. Back to the story.
So,  whilst she was chatting on line with one of the lads who's going with the party, he inadvertently (or not -  jury's still out) misspelled the word "you're" - without the apostrophe or the 'e'.  (The sentence was something like "your an idiot" - feel free to replace stronger, more insulting teenagery-type words at will).
Gulp.
This is MY daughter we're talking about, so you kinda get the gist of where this is going, right?
She corrected him.  Only decent thing you can do.  He stuck to his guns, telling her he was using it as slang and as he's currently mid-way through A-Level English Language, he should know.
Double gulp.
The Girl pointed out that if he'd wanted to use the word as slang or even 'text-speak' then it should have read something like"ur"  and not just missed out the apostrophe.
Heated debate (again, use your own imagination) ensued.
Fine.
Lots of 'fine's during supper this evening.  a few tears.  a few more.

[I have to interject that MY advice: "A Mother's Advice" - which was actually sought, may I add - was that the whole thing should be "slept on" and re-visited tomorrow after the heat of this evening had been allowed to chill a little.  No rash decisions should be made until then. Very sensible I thought.]

Consequently, lad is told that until he apologises and admits his inaccuracy, he is no longer welcome on this pre-arranged outing of musicality.
Nothing like a sound piece of advice being put to good use.  Nothing like.
He stands his ground.  He knows what he's talking about.  The A-level course again cited as proof if proof were needed.
So another girl is invited in his stead.
An hour later he apologises.

[Of course very, very tempted at this stage to go with an "I told you so", but a Mother knows her place]

And after he's informed of being usurped in the Kerrang seats, tells the Girl that of course he's not upset, and he wouldn't dream of demanding he still goes after she's already replaced him.
There's a moral in here somewhere but for the life of me, the only one I can come up with right now is "Mother knows Best".