Sue Arnold: One mother is an asset - two would be a liability

The idea of having another ageing mother in a granny annexe moaning about the children is daunting

The latest news from Newcastle - that doctors have been given the go-ahead to create a human embryo with two genetic mothers - may well be a scientific breakthrough but socially it sounds like a recipe for disaster.

Most children have a hard enough time trying to cope with one mother; imagine what it would be like to have two under the same roof fussing over what you eat, what you wear and whom you're going out with.

Theoretically, of course, the situation would never arise. The sole aim of the medics engaged in this particular research is to avoid the risk of mother passing a range of incurable hereditary diseases onto their unborn children and no doubt numerous legal constraints will be set up to protect the anonymity of the partner-mother.

Still, the way things are going in this in-yer-face, let it all hang out society we live in, there's a strong chance that in some cases the two mothers will want to get together and bring up their shared child even if it's only out of curiosity to see which bits of them the child has inherited.

That, of course, will be the first stumbling block. Mothers are so competitive. The bragging starts pretty much the moment their children are born. Listen to them at post-natal check-ups boasting to the nurses how much more weight their babies have put on in the past week than their friend's sprogs or how much more hair they have.

Fast forward three years and the same mothers will be telling you how many Dickens novels Kylie has read or what Joshua's violin teacher said about Joshua's extraordinarily precocious musical talent. And now imagine, if you will, what it would be like to have two mothers arguing about which of them is responsible for Kylie's advanced reading ability or Joshua's artistic flair.

Mind you, with two mothers in the house life would be a permanent argument. It is a truth universally acknowledged that a single room containing 100 mothers will not produce two women with similar views about child rearing.

It is the one subject about which every mother believes she knows better than anyone else. Years later maybe (and I speak from bitter personal experience) you may wonder if it was wise to send your little treasures pony trekking in Aberystwyth in February to toughen them up or to stay with an eccentric relative in Bruges. But at the time you can be damn sure you knew that you were doing the right thing.

With two mothers it is doubtful that the poor child would go anywhere at all so adamant would each mother be as regards the perfect holiday venue. Mother A would have her suggestion of a jolly two-week bucket-and-spade break in the West Country rubbished by Mother B who has her eyes firmly fixed on a fortnight in Italy dragging the child round churches and art galleries. For, as everyone knows she will say, you cannot begin a child's education into the glories of the Italian Renaissance too early.

And what about food? If one man's meat is another man's poison, then one mother's idea of a healthy diet for a growing child is another mother's junk food. I shall never forget a birthday party we had for one of my children aged about four which was full of mothers with strict dietary principles - no sweets, no soft drinks, no snacks between meals. "Would you like an egg sandwich, Samantha?" I asked one of the children. "Are they free range?" she asked in reply.

Having dwelt at some length on the delicate situation of the mothers in this curious ménage, I appear to have overlooked the role of the father.

What role? you ask. Exactly so - what role? The chances of any normal man having much say in a household containing two mother figures are minimal. Hang on, am I being incredibly naive? How do Mormons and Muslims and all those other religions that go in for polygamy cope?

I have been looking at this whole issue exclusively from the child's point of view, but that's probably because the idea of having another ageing mother in another granny annexe complaining about the mess the children leave in the garden is daunting.