WHEN I hear the phrase "designer baby", I picture a tot dressed from head to toe in Jean Paul Gaultier. Stupid, I know, but the idea of a baby in a mini kilt and conical bra appeals to me more than the bizarre notion of creating a child using a genetic recipe dreamed up by perfectionist parents.

The futuristic concept of picking and choosing a child's characteristics before a sperm has even got its arm-bands out of its swimming bag and popped on its goggles makes my head spin. At the best of times, science leaves me with a quizzical expression on my face and a less than articulate "eh?" on my lips. But this bit of scientific jiggery-pokery leaves my mind in an even more boggled state than usual.

There is something about this giant medical step forward that makes me think it is a step too far, a step we just weren't supposed to make. I mean, aren't babies supposed to be a genetic hotchpotch of the good and bad things that make us all human? Aren't our kids supposed to be individuals who surprise, bemuse and delight us in equal measure?

Life would be boring if our children were predictable down to the last gene. Personally, I don't even want to know what flavour my baby is until it arrives - hopefully this week, with good luck and a following wind - never mind what colour eyes it will have and whether it will have a built-in talent for pitch and putt golf later in life.

Up until now, designer babies have been something of an abstract concept involving parents with more money than sense choosing whether Junior will be blonde, blue-eyed and a hit with the ladies or a mad, moody mathematician with a brain the size of Bermuda. But after last week's surprise Court of Appeal decision in the Zain Hashmi case, it is no longer a futuristic notion worthy of Arthur C Clarke, but a scientific reality.

I have every sympathy for four-year-old Zain, who has a genetic blood disorder that will, if left untreated, lead to his painful and untimely death, and for his parents, Raj and Shahana, who have fought doggedly for the right to select a test tube baby of the correct tissue type to treat their son. Which one of us wouldn't have done the same in their shoes?

But I can't help thinking that the surprise announcement by Lord Phillips, the Master of the Rolls, that the Human Fertilisation and Embryology Authority did have the power to licence embryo selection by tissue typing - overturning a previous High Court decision - was opening the door to a heap of trouble.

In the short term, the Hashmis and other couples in a similar situation can now use IVF to ensure that cells from a test tube baby's umbilical cord are compatible with those of a seriously ill older brother or sister. It is difficult to be ethically opposed to the procedure in such circumstances, but it is also not difficult to see how this victory could be abused in the future.

A technology used to save sick children today could be used to design perfect accessory babies to match parents' designer lifestyles tomorrow. And in the meantime, we have to consider what sort of future we are creating for the children produced as medical lifesavers.

During the hearing, Mrs Hashmi was allowed to show the judges photographs of her son lying in a hospital bed, telling them: "He is not just a name. He is a little boy of character."

This is undoubtedly true. But what of the nameless little boy or girl she and her husband are hoping to create to help Zain? In all the reports I read about this landmark decision, not a single mention was made of the new baby, the little boy or girl of character who will be whipped up in a test tube with the primary aim of saving their sibling.

I understand that for the Hashmis the end justifies the means, but I can't help worrying about where society will eventually draw the line.

Updated: 11:32 Tuesday, April 15, 2003