In a children's clothing shop recently, I heard a young mother shout expletives at her three-year-old son, who shouted them right back. She then smacked him viciously and when her baby daughter started crying, she smacked her too. Those of us who witnessed the assault felt powerless. Here are three thought-provoking facts to remember, just in case you ever start taking your own parenting skills for granted: smacking children can make them emotionally and intellectually `'dumb" and children whose parents hit them regularly have lower IQs than children whose parents never or rarely punish them physically; babies whose mothers are depressed react negatively to their mothers and to strangers, indicating that they have already learned to see the world and other people in a negative way; children who are deprived of close, affectionate physical and emotional relationships with caring adults grow up not just emotionally stunted, but physically stunted as well. This mother - who undoubtedly had traumas and stresses of her own to cope with - was literally moulding her children's brains to make them physically violent and emotionally numb. TCD psychology professor Ian Robertson explains how this happens in his book Mind Sculpture: Unleashing the Brain's Potential, which has just been issued as a paperback (Bantam, £7.99 stg). In it, he describes how parents "sculpt" their children's brains - literally guiding the physical structure of the brain by the way they relate to the child. "What an awesome responsibility it is, physically shaping a child's brain like this. The words we speak, the actions we take, sculpting the brain as surely as any surgeon could," he writes. This sculpting occurs every time neurones fire in the brain, creating patterns of connections in the electrical web of the brain. Cells that fire together, wire together. When neurones keep firing in particular patterns - whether in reaction to classical music or to being cuffed on the ears - the more likely it is that the brain will take on these patterns permanently. Thus, children who are hit, become children who hit. Children whose mother's don't smile and respond to them, become children who don't smile and respond. Children who are not loved, physically wither and become adults who cannot love. Children who are told to hate Catholics or Protestants, become phobic about Catholics or Protestants and have difficulty overcoming this, even if they intellectually reject the notion. The huge potential in children to be moulded for good or ill is quite terrifying. Mothers give language feedback to their infants approximately 2,000 times in a 24hour period. Over several years of childhood, this corresponds to millions of carefully crafted coaching trials and moulds the brain's connections.

Robertson believes that we are all born with basically the same raw material in our brains, but that some of us are able to make the most of it through nurture and education, while others of us are not. For example, a stressful childhood can drench a child's brain with the steroid stress hormones, shrinking neurones and dramatically lessening the child's ability to learn and remember so that they never achieve their intellectual potential. On the positive side, any child can be a "genius" or "virtuoso" musician given the right tutoring and plenty of practise, Robertson argues. The question is, do we really want to hothouse our kids? Life is about more than goals and achievement, after all. But there's no doubt that your child can achieve far more than you expect, given the right education. Next time you watch your child doing homework, consider that each neurone in your child's brain has up to 50 per cent more connections than yours. Even when children are not being taxed by new learning, their brains are more active than those of adults. This is because children have a greater number of synapses - or connections - between neurones (nerve cells) in the brain. A seven-year-old has 40 per cent more synapses per brain cell in the frontal lobes and is at a peak of connectivity. Remember the Jesuit saying: "give me the child at the age of seven . . ."

So, given this huge potential, how should we nurture our children's brains? By talking to them, even in the womb. By the age of three, the average child of a professional family will have heard approximately 30 million words addressed to him or her. A child of a working class family will have heard 20 million and a child of a family on social welfare will have heard 10 million. However, childcare arrangements can change this balance because children looked after by parents, relatives and childminders - whatever their social class - have larger vocabularies than children cared for in private day-care nurseries. The study was conducted in the 1980s and, no doubt, most Irish creches and playschools are far more responsive to children than this. But you can't argue with the fact that the brain "craves the caresses of stimulation and learning," says Robertson. Children can catch up, but the bottom line is that "how well language will develop, and hence how well more general mental abilities will develop, does seem to depend on how well parents - and particularly mothers - conduct the millions of brain-shaping coaching sessions involved in rearing a child."

So even if you are just talking to your child as kindly, responsively and frequently as you can muster, don't take yourself for granted. You may not be a rocket scientist, but you are a darned good brain surgeon.