IT’S just when the doorbell rings that I notice the silver star hanging from the light fitting – a single remnant of Christmas that escaped the annual exodus to the loft.

Normally this wouldn’t be a problem, although it does reflect badly on my dusting habits.

But on this occasion it spells disaster.

The friend who is at the door, ringing the bell, is allergic to Christmas decorations.

Not in December, you understand, which is the right and proper time to display them, but at any point outside the official festive season.

A single star in February she might just about be able to cope with, fighting down the nausea as she turns her back to the offending bauble.

A grinning Santa on a roof in August or a Nativity scene in July, however, would send her spinning beyond the point of no return.

And it’s not just Christmas decorations – anything that’s found itself out of place appears to have a disagreeable effect on her inner ear.

I once mentioned seeing zebras living wild among a herd of cows in California, and was speared with a warning look before I’d finished my sentence.

She and another friend, suffering from the same condition, insisted that the sight of a non-indigenous species would have ruined their day and would have gone a long way to spoiling the two-week road-trip we were right in the middle of.

The other friend was still in recovery from realising the grass in Las Vegas is made of plastic – something I am sure she still has nightmares about.

I had managed to steer her away from the libretto-singing fake gondoliers on the fake Grand Canal in the fake Venice before the shock became too much.

Intriguingly, they are two of my most level-headed friends, the people I would turn to in a heartbeat for good, solid advice.

It’s as if the bit of their brains that deals with tinsel and zebras is making up for the 99.9% that operates with far more than average common sense.

But we all have our little foibles, the things that irritate or make us feel uncomfortable, when our reaction seems entirely irrational to others.

I hate pots and pans not sitting in order of size in the cupboard, or drawers that are too full.

I am regularly tempted to empty the whole lot into the bin, because the thought of dealing with the problem makes my skin crawl.

I can’t stand the tiniest bit of pith on a segment of tangerine or the texture of a peach against my tongue.

And if you’re a woman who’s going to start talking in a baby voice, please wait until I’m out of the room.

My boyfriend always has to have a knife and fork on the table when he’s eating, even if it’s finger food.

And if you pause Sky Plus for just a second, he feels the world is out of sync and the sky might fall in.

Another friend feels close to panic if her car isn’t equidistant from the two white lines in a parking space.

And I know from practice that you can drive my sister to distraction simply by inventing shortened forms of everyday words.

What primal reason is there for these instincts, I wonder, because there seems to be little that’s rational about them?

Was one of my caveman ancestors once exfoliated to death by a peach or flattened by a pile of primitive giant saucepans?

Did my friends’ great-great-great-great-great-great grandparents get put in the stocks for celebrating Christmas in August?

And what of future generations?

Perhaps they’ll develop an unexplainable aversion to people with unexplainable aversions.

That would certainly explain a lot.

READ more of Laura’s columns at www.liverpooldailypost.co.uk/lauradavis