You're buying a book. Stop trying to fill the world with mumbo jumbo.

Oh, and also, you're killing your daughter's intellect. You're bad parents. And you really need to rethink your personal hygeine.

This was the reaction that exploded into my LED-adorned Santa hat bearing head as I tried to help a husband and wife buy for their daughter today at the big W. If I had said this, quite probably I would now be drinking to my reasonably lengthy job there as it swanned away. But I didn't voice my opinions, or the facts, and simply advised them on what each of the many books we "tried for size" held within their pages.

It was a fun half hour.

My first point is this. If you want your eleven year old to not encounter dark and depressing characters in films, TV and books, don't let her get into those series. Don't let her read the whole of Twilight and other series and then decide no, vampires are the seductive evil, that which she shall not read of.

If you do that, you are a moron. Mostly because you actually tell the shop worker that filling your daughter's head with negative energy and vibes is not something you want to do. Explaining in no uncertain terms that yes, this does mean what it seems to, and that you believe by reading about bad things they manifest in the reader's mind and soul, does not help the situation. It just reinforces your own overabundancy of unimaginable naivety.

Even then, here's a few little tips. While I try and tell you what is involved in the latest Terry Pratchett YA novel, DO NOT contradict me. I am the bookshop worker. I know about the book. Or I tell you I don't know and will get someone who does.

Drawing the line at mythical beasts and fantastical creatures such as vampires or demons is fine, if you genuinely don't want your daughter reading about them. Personally, I think that's the right age to be introduced to the "not everything is good and positive" complex that is life. But that's by the by. Next rule I'd love to impose- don't apply double standards. Darren Shan is in 9-12 yrs for a reason- he's suitable. Demons= no while dragon slaying and dark spirits possesing bodies= yes in Eldest, also in 9-12 yrs, is a stupid way of doing things.

DO NOT try to score points with the bookshop guy about who's read what. I don't care. Asking about fantasy books, particularly those with elves, expect LOTR to come up. Don't then state that The Hobbit is too dark for your lovely dear eleven year old, and when I contest that saying I read it at ten and was fine, try to beat me by saying by eight you'd read it twice. You've undermined your own argument and shown yourself to be a dickhead.

DO NOT tell me that Dracula and LOTR are great books, challenging enough for your eleven year old but too dark for her, then insist that every single Discworld Pratchett joke based on wordplay is understood by your eleven year old, while in the next breath saying that maybe The Hobbit is too confusing. There are so many things wrong with the order in which you have just positioned these texts in terms of confusing the reader that I don't know where to start. When I say so, do not insist that honestly, she completely understands everything in Discworld because your household all have very Pratchett-esque senses of humour. I have two feet. That doesn't mean that in pre-teen years I could run a marathon across hot coals barefoot. Picking and choosing when she's too old for something is one thing. Picking and choosing a bunch of completely similarly suitable texts and putting them at opposite sides of a hexagonal spectrum of what she needs to read to fill her with happiness and light to combat the evil of her soul enchanted by words on a page is cack-handed and suggests hereditary psychological problems.

Last rule- don't ask about fantasy adventure books, a genre which you claim to know very well, and expect not to come across monsters and antagonists that are dark, magical and reflect the evils of this world. Your kid's eleven, learning that heroes sometimes have to fight big reptiles or magicians. She's not a three year old being presented with a rapist waggling his bits in her face. Grow some balls and do some parenting.

In twenty years time, when she discovers great books with dark and light elements together, including classics, goes crazy because you kept them from her, and tries to kill you all, don't come crying to me.