It is a crisp January morning on the outskirts of Colorado. Julie Wilber, a registered nurse from the hospital in Denver, has just made a 15-minute drive to visit Leah, 28, mother of Lance (who is just one). Dressed in an old jumper, Julie looks like a friend or relative as she rings the doorbell, but the stack of notes and stethoscope sticking out of her bag tell another story.

The house is messy – as homes with children usually are. Leah apologises, but Julie tells her not to worry. They settle down together on the floor of the sitting room with Lance toddling around between them. They discuss his diet (he likes chicken and pasta) and his physical development.

Then Julie hands over a “Mom’s memo” (some suggestions for activities appropriate for his age). Julie is a paid professional but what she is giving is the kind of support that I got from my mum and friends when I had my babies.

Julie is part of the “Olds model”, a nurse/family partnership for mentoring new mothers that runs in 20 states across the US. She first met Leah when Leah was only 12 weeks pregnant and has been seeing her at least once a week – often more – since then.

The Olds model programme began 30 years ago and helps low-income first-time mothers whose children are most likely to be at risk. By the age of 15, children who have been involved in this programme are 69% less likely to have a conviction than those who haven’t. Other indicators are similarly impressive. The programme is incredibly successful at improving the life chances of the most vulnerable group in society.

Gordon Brown’s government is obsessed by improving the life chances of the poorest, most vulnerable children. There is a stubborn rump of families who seem doomed to a cycle of disadvantage – the Vicky Pollards, those single mums on sink estates having children while still children themselves.

Often they are the offspring of young mums or, worse, were in (that great misnomer) “care”. Billions of taxpayers’ cash has been poured into programmes such as Sure Start to try to reach these kids. Brown bangs on about “no child left behind”, but no matter how many creches and Sure Start centres mushroom around us, the cycle of doom continues.

The latest figures have it that by 22 months – before children are even two years old – there is a massive gap between the sink estate kids and the rest. Brown – in the guise of his emissary Ed Balls at his new super children and family ministry – has come up with yet another plan to fix this: a compulsory curriculum for kids under five where children aged three and four will learn to write simple sentences, interpret phonic methods to read words and use mathematical ideas to solve practical problems.

The thinking behind this is that the new rules will force nurseries to give underclass kids the stimulation that their middle-class brethren take for granted. That by decree they can ensure a helicopter mummy, Baby Einstein curriculum for all where everyone knows their ABC before they even get to nursery. The reason they are so worried is because the knowledge gap between different kinds of kids by the time they get to nursery is already so huge. At first glance it looks a laudable plan.

The problem, I’m afraid, is that Brown’s new underfive curriculum is unjoined-up thinking at its worst, as it ignores the basics of brain chemistry. Neuroscience shows that emotional experiences in infancy have a measurable effect on how we develop as human beings; our earliest experiences of social interaction are translated into precise physiological patterns of response in the brain that then set the neurological rules for how we deal with our feelings and those of other people for the rest of our lives.

It is all down to the hormone called cortisol. When a baby is upset, the hypothalamus at the centre of the brain produces cortisol. In normal amounts that is fine, but if a baby is exposed for too long or too often to stressful situations its brain becomes flooded with cortisol, and it will then either overor underproduce cortisol whenever the child is exposed to stress.

Too much is linked to depression and fearfulness; too little to emotional detachment and aggression. Babies can’t regulate their stress response on their own; they learn to do so by the reaction of their carer when they are upset.

When the baby’s needs are met, the brain learns to produce only beneficial levels of cortisol. What the science shows is that good parenting isn’t just nice for small children; it actually leads to proper development of the baby’s prefrontal cortex, which in turn enables the child to develop self-control and empathy and to feel connected to others.

I have always been haunted by those Romanian orphans, left alone to cry in their cots from birth with no mummy to love them. Well, when scientists studied their brains, they found a virtual black hole where the orbitofrontal cortex should have been (this is the part of the brain that enables us to manage our emotions, to empathise with others, to experience pleasure and appreciate beauty). Turns out that I was right to be haunted: the lack of love had inhibited their capacity to be fully human.

The point about my mini brain science lecture is that there is no point in taking kids who have been appallingly badly parented – whose brains haven’t been programmed right, because their needs haven’t been met – and expecting that they will be able to absorb the kind of education-based nursery curriculum that the government has in mind.

One psychologist told me that it’s like pouring water into a bucket with no bottom. The maths and phonics won’t stick. The brains of these very deprived children are simply not chemically wired well enough to be able to learn.

David Olds, who invented the US programme, recognised this 30 years ago when he worked in an inner-city nursery and realised that some three-year-old kids were already so damaged that they couldn’t learn. That is why he started to intervene when the mothers were pregnant. Such kids physically cannot behave in the way that Brown’s new underfive curriculum wants them to.

The reason the Olds nurse programme works is because at-risk mothers have one-to-one support from a nurse/midwife substitute from early pregnancy. These people coach vulnerable women, many of whom were never parented effectively themselves, in how to be a responsible and loving parent and how to meet the child’s needs. Crucially, the nurses also provide emotional support, so these young mums have the confidence to do better. And it works. By the age of six, nurse-visited children had larger vocabularies and higher IQs.

The good news is that the Olds model is beginning to be piloted in Britain. The bad news is that Brown’s muddled thinking and insistence on a one-size-fits-all underfive curriculum won’t just not work for the most vulnerable. The severity of its prescriptions will also kill off the more free-form nursery approaches beloved by Montessori and Steiner groups, which believe in introducing more structured learning later. Many parents – me included – happily pay for this different approach.

By all means help the poorest, Gordon. But don’t kill off choice and other proven methods chosen by the rest of us in a misguided attempt to help the vulnerable.

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