"When are you supposed to start flossing your children's teeth?" asked the fresh-faced young American mother of an 18-month-old, sitting opposite me in the doctor's surgery. Hell's teeth, I have enough problems getting my hands into my own mouth, which is why my flossing resolutions never last beyond three days after my visit to the dental hygienist. I suppose she thought that a mother of four would have all this kind of thing sussed by now and that we looked like a shining model of family health and hygiene. If only she knew. My four-year-old and eight-year- old both have fillings (you tend to give up the puffed-rice-cakes-only regime after the first baby) and all this week we have been bonding over the nit comb. Instead of feeling pleased that the male side of the family has escaped the scourge of head lice, I have been worrying that I don't have enough head-to-head contact with them. And we were sitting there in the doctor's surgery because I wanted to have one of the boys' moles checked out, just in case the three bottles of Factor 30 we got through on holiday hadn't been enough to stop a few rays of carcinogenic sunshine getting through. As usual, I had to content myself with the doctor's reassurance that my son's only affliction was a paranoid mother. This probably wasn't the time to mention that my medical dictionary also says that head lice can transmit the organisms of typhus fever ...

Return home to look up "hypochondria" in my dictionary of symptoms but instead my attention is caught by "Jeep Disease", which can be identified by a "discharging spot, perhaps with a tuft of hairs sticking out, releasing a bloodstained, foul-smelling material, in the cleft above the back passage" and is so named because it is thought to be caused by sitting on a hard and vibrating seat, as in a Jeep. It isn't often that my medical books cheer me up, but this casts a whole new light on people who think it's cool to drive round London in farm Land Rovers, doesn't it. My suburban Renault Espace has never seemed so attractive.

But back to hypochondria. I had always attributed my own case to childhood exposure to Emergency - Ward 10 and Doctor Kildare but I now find that it may be "a defence mechanism in work failure or marital failure or a self-punishment for imaginary guilt". It doesn't say anything about heredity but I fear my 10-year-old son has it worse than me. I don't think I can be blamed for this - I have always tried very hard to conceal my hysteria if the children cannot pinpoint the exact origin of a bruise (bruising comes under leukaemia, just as headaches come under brain tumour, in my mental index of symptoms). Nor is it the fault of television - the children's unhealthy interest in Casualty is obviously a symptom, not a cause. No, I blame the trend for social realism in children's literature. At the age of eight when most boys have a natural interest in comparisons (or so it says in one of my child development manuals, shelved next to the medical dictionaries), instead of asking whether you would prefer to be a pop singer or a footballer, my son was posing teasers like "would you rather have muscular dystrophy, cerebral palsy or dyslexia?" - all of which were starring ailments in novels he was reading at the time. Now, despite being a strapping, healthy boy, he is convinced that I am concealing some mysterious illness from him. "Are you sure this holiday/meal out/packet of sweets isn't just a final treat for me?" he demands suspiciously, whenever we even border on being nice to him. In retrospect, I should have swallowed my intellectual pride and let him loose on Enid Blyton.

Bereft of our nanny (yippee! I can throw away Tesco carrier bags and left-over food without feeling guilty - inside her young and glamorous facade, Kelly has the spirit of someone who has lived through two world wars) I have sent the three oldest children off to stay with my parents in the country for a holiday free of medical paranoia. And what is the first thing my mother does with them? Takes them to the veterinary surgery where, she says, the nice vet man showed them how to "squeeze dogs' bottoms". Yes, really. Apparently, explains my oldest son over the phone, dogs have these musk glands in their rectums (hence the traditional form of canine greeting), which sometimes get blocked. The children may have missed out on summer school, but it's good to know they've picked up some really useful life-skills this summer.