My daughter was about 2 years old when I found out that I have HNPCC. One of the first things that I asked the genetic nurse who broke the news to me was: when can I find out whether my child has the gene?

Her answer was that I can’t find out until she wants to find out for herself. The genetic testing is usually done somewhere around the ages of 18-23, but they will do it a bit earlier if the child requests it.

At the time I thought: I just want to know NOW. But now I realise that this is a very sensible strategy. HNPCC does not start affecting you until you are in your early 20s, so there’s no medical reason to find out whether the child has the gene. And it’s a funny kind of thing to know, because it doesn’t affect your day-to-day life at all – it is a risk, not a disease. It’s perhaps not the sort of thing that a child can be expected to cope with knowing. (It’s tough enough for adults.)

I’ve never tried to hide my annual visits to the doctor from my daughter. She watches me drink the horrible Colo-Prep brew and she knows I don’t like it. She understands that I have to be sick for a day or two, and that the doctor will then stick a camera up my bottom to see if my insides are healthy (this bit she finds hilarious).

Of course as she gets older, she’ll start to understand more and more about it, and I have no intention of hiding anything from her. Once she’s old enough to piece together the fact that most of the family has to do this once a year, and she says “will I have to do this one day?” I will tell her that she might have to. But by that time I hope she will not find the prospect shocking or scary.

So, knowing what I know now, would I have another child? This is a difficult question, and one that I have pondered a lot. Is it right to have a kid if you know for sure that the child will have a 50% chance of having HNPCC? Shouldn’t you rather abstain for the love of that unborn child?

My conclusion has been that HNPCC should not stop you from having kids. And my main reason for saying this, is that I’m rather grateful to be alive. I mean, I would rather have been born than not, even though I have this condition.

I’m also very lucky because I discovered I have the gene before actually getting cancer, and my children will be in the same position. Many people with HNPCC only find out about it after the crushing blow of being diagnosed with cancer at a very early age. I have been in a screening programme since I was 25, and my doctor tells me that people who are in a screening programme have the same life expectancy as anybody else. My daughter, and any other potential offspring, will be screened as soon as they get to the age where it becomes necessary – if they have the gene.

I have discussed this with my doctor, who says that I shouldn’t let it put me off. In fact he strongly encouraged me to have another child. He says the condition is manageable, and so far it looks to me like he’s right. Of course, life (and my genes) could punch me in the nose tomorrow.

When I shared this moral dilemma with my best friend, she said I should consider the fact that I will also be passing on my genes for good looks and a sparkling personality! (That’s why she’s my best friend.) But really, the jury is still out on whether I get myself knocked up or not. There is no denying that the prospect of passing HNPCC to your child weighs heavily on the mind.

• A disabled mum writes about passing on your genes in The Guardian
• BBC News reports British people can now have embryos screened for HNPCC

It is never a joyous event when your doctor tells you it’s time for a colonoscopy. No one in their right mind would relish the prospect of having a camera shoved so far up their arse that it tickles their small intestine. In fact, the first time I was booked in for a colonoscopy, at the age of 23, I was so mortally afraid of this procedure that I didn’t even bother to show up. At that point in my life it was more than just fear of the colonoscopy – I also couldn’t bear the thought of asking a friend to pick me up from the hospital afterwards. It was just too embarrassing to even think about, let alone discuss with another human being.

Ten years later, and things are somewhat different. In the last 7 years I have had 3 colonoscopies, with the 4th due tomorrow. And although a colonoscopy is no walk in the park, it’s not nearly as bad as you think it will be.

The ordeal usually starts the day before the procedure, when you need to empty your bowels of all its contents. Your day will start with a glass of Colo-Prep, or some similarly named drink: a sachet of powder that is mixed with water and tastes so evil I am convinced the devil himself developed it in his subterranean laboratories. Drinking this stuff is by far the worst part of the entire procedure. It tastes like a mixture of chalk, metal, and pure evil, and they often try to mask its satanic origins with a dash of lemon flavouring. Ugh.

About 30 minutes or so after drinking the devil’s potion, you will find yourself running for the loo. I’ve had Delhi Belly (authentic, I might add, in the holy city of Varanasi on the shores of the Ganges), and this is quite similar. For the next two hours you must pour litres and litres of water down your gullet, and it will pour and pour out of your bum. Firmly stuck on the loo is the only place to be. The potion can also make you feel a bit nauseous, or give you the shivers, or give you heart palpitations. Just keep pouring water down your throat, it will all be over in a few hours.

But then! Just when you have dragged your poor battered body off the bog, it will be time for your second glass of Hell’s Vintage. The cocktail is usually 2 glasses of the stuff, about 6-12 hours apart. So off you go again, holding your nose while you drink it, fighting the nausea, wondering how anything can possibly taste that bad. And off to the bog again, for another two hours.

By the end of this, you will certainly feel like you have been dragged through a hedge backwards. Twice.

Now it’s time to go to the hospital. And believe it or not, this is the easy bit. They will put you in a gown that’s open at the back, and ask you to lie down on the bed. You’ll see a big machine with a long black tube attached to it, about as thick as a super size tampon. This machine also includes a TV, on which you can watch the procedure if you’re that way inclined. (I prefer to be knocked out cold.) You’ll have to lie on your left side, with your bum facing the doctor. At the other end there will be a nurse, who administers the sedatives but whose most important function is to hold your hand and reassure you.

They’ll put a needle in your arm, and shoot some Dormicum and Pethidine in there. I believe one is a painkiller and the other a sedative. You won’t be knocked out, like with a general anaesthetic, but only a shred of your consciousness actually remains in the room. If you feel anything at all, you can feebly cry out (feebly, because you’re very drowsy from the drugs) and they’ll just give you more. Sometimes there can be a little pain in your tummy, because they have to blow air into your colon, but on a scale where childbirth is at the top end, and stubbing your toe at the bottom, this pain is so minor it’s close to the toe-stubbing end.

Next thing you’ll know, you’ll wake up, sort of. The doctor will tell you whether he’s found anything, but you will forget what he said almost as he says it. Ditto for anything else that happens. It takes about an hour for your mind to fully come back, during which time you will ask the friend who brought you to hospital about 10 times: “What did the doctor say again?”

And that’s a colonoscopy. Now that I’ve been through one several times, I can’t believe how afraid I first was of having that pipe up my bum. You really don’t even feel it. Your bum doesn’t hurt in the slightest bit afterwards. By far the worst part of the whole procedure is the devil’s drink and the diarrhoea – and we’ve all had the shits at some point in our life, haven’t we?

I inherited two things from my grandmother: a delicate Royal Albert tea service, and a genetic condition called HNPCC. I would have preferred to have just the fine china, really. My grandmother’s gene gives me an 80% chance of getting colorectal cancer, 40% chance of getting womb cancer, and slightly lower odds on a veritable smorgasbord of other cancers.

Of course, my grandmother first passed this gene to my mum, who didn’t know about it. She had colorectal cancer at the age of 37, her womb removed at 39, and cancer in what little remained of her colon at 49. Pretty grim. I am at a huge advantage compared to my mum: I know I have the gene, and I’m in a pretty intense screening programme.

Now let’s just be clear about one thing: I don’t actually have cancer. Not yet. At the age of 26 a gastroenterologist removed a polyp from my colon, all of 2mm big, that exhibited ‘mild dysplasia’. That means the little polyp would have grown up to be cancer, something that caused me mild displeasure. That was 7 years ago and nothing untoward has been found since.

And yet last Friday I was sitting in the office of a venerable professor, a colorectal surgeon and an expert on inherited bowel cancer, and listening to this man tell me that I needed to have my colon out as a preventative measure. It wasn’t the first time I’d had such advice – earlier this year an equally eminent gynaecologist advised me to have a full hysterectomy, as a preventative measure. If I’d listened to the doctors I’d be sitting here, aged 33, in the full swing of surgically induced menopause, and minus a colon. In fact, I probably wouldn’t be sitting here, I’d be on the bloody bog trying to cope with the reality of life without a colon.

There is one comfort, and only one, in having HNPCC. The ‘H’ stands for ‘hereditary’, and that means you’re guaranteed to be surrounded by family members in the same boat. My brother was with me in the professor’s office, and put it beautifully: “It may be a bad colon, but it’s MY colon, and you’re not taking it out.”

They made a pretty strong argument for having a colectomy (that’s snipping out the old colon to me and you). They made it sound like life would swing on as always, apart from the fact that you’d skip serenely through your days knowing that you can’t get colon cancer coz you ain’t got no colon. But this is the 21st century, and I don’t take anything at face value. So of course I hit the internet to see what other doctors were saying.

I’ll be honest: there are many doctors who agree. A bit of major surgery to snip out the offending organ, and you’ll never have to think about it again. However, delving through the BMJ archives I found a study saying that undergoing this very major procedure would only add about 2 years to the life of an HNPCC patient. The particular study suggested that 2 years wouldn’t be worth the discomfort of living without a colon, and I heartily agree. Or as my ever-witty brother pointed out: “You’ll be spending most of the extra time on the bog anyway, and where’s the joy in that?”

I’m 33 years old and there is nothing wrong with me. By that I mean that I am not ill, nor do I have any symptoms of any kind of illness. But I won’t deny that there is a cloud hanging over me. Some days it’s a wispy little thing, barely there. Other days it’s a brooding black thundercloud that makes me feel I might as well blow my brains out because I’m screwed anyway (those days happen when I’ve been anywhere near a doctor).

But here is what I choose to believe about HNPCC, most days. It gives me an 80% chance of colorectal cancer, and 80 is not 100. My gran lived until the ripe old age of 59 before she had to have her womb out, and only succumbed to colon cancer at the age of 72. I am screened for all the cancers I’m most likely to get, every year. This hugely reduces my chances of actually getting it. I might live to a ripe old age like gran, or I might get run over by a car this afternoon. Brooding on my faulty DNA will get me nowhere. Being sensible and having a camera up my arse once a year – well, that may just get me to a ripe old age too.