One of our most cherished dreams as parents is that our children should be the best of friends. To see them fighting, pulling each other's hair, grabbing each other's toys, or constantly bickering and squabbling, can be a distressing and bewildering experience. Often we blame ourselves.
But what lies at the root of sibling aggression? How much is it affected by difference in sex, or difference in age? Why do some brothers and sisters get on so much better than others? To what extent are parents the cause of it, and what can they do to make it easier for children to get on together?
Juliet Hopkins, a child psychotherapist at the Tavistock Clinic, in London, says that rivalry between siblings is not only common but is perfectly natural. "It comes from human nature that we are inevitably competitive and want the best for ourselves. Sibling rivalry can be seen as a healthy way of laying claims on your parents, just as a certain amount of jealous possessiveness between a husband and wife is a good way of keeping off outsiders."
Whereas a first child who has enjoyed a particularly close relationship with his or her mother may find it harder to accept a new brother or sister, a child who has spent a lot of time with a nanny or childminder may find it easier, "because they have come to expect a less high level of devotion from their mother", says Mrs Hopkins.
If the relationship with the parents is poor, siblings are likely to be allies: a certain amount of rivalry between siblings is a sign that parents are worth competing for.
The age gap between children is much less significant in determining the quality of their relationship than is often thought. Although a gap of five years or more can make it easier, it is impossible, many specialists believe, to generalise about the respective merits of a two-, three- or four-year gap.
Judy Dunn, a research psychologist, made a study following first-born children from before the birth of the second child, and found that age gap and gender were not related to the interest shown in the baby by the older child. A key factor was the child's temperament; anxious children, for instance, showed little affection for their new sibling. Also important was the nature of the parents' relationship with the first child before and after the sibling's birth. First-born girls, for example, who had had an intense, playful relationship with their mothers were notably hostile to the baby; and these babies, by the age of one, were also showing hostility to the first-born.
Sibling rivalry is not the fault of the parents, says Lisa Miller, a child psychotherapist at the Tavistock Clinic, but the way they handle it is crucial. "We can contribute to sibling rivalry without realising it. If you are really rather frightened of it, when you see the slightest sign you may be alarmed: you may get very cross or you may deny it - both of which will make the rivalry worse."
It is common for children to feel both affectionate and hostile towards their siblings. "All children have mixed feelings," says Mrs Miller. "We need to recognise that a child behaving aggressively is in conflict; children don't want to be nasty to each other, but because they are immature they have feelings they can't control."
Parents need to acknowledge the power of these feelings, and help the child to express them in a way that will not harm others, advises Tim Kahn, of Parent Network, whose discussion groups for parents include special sessions on sibling rivalry.
"If these early feelings are not drained of some of their power, the two children will very easily get locked into playing out the rivalry between them," he says.
A child who is reacting violently to a new sibling could, for example, be encouraged to take his feelings out on a doll or soft toy; but it is important for the child that parents witness and acknowledge that anger rather than sending the child to another room - which would feel like a punishment.
Drawing the older child into talking about the baby, what it might be needing, why it is crying, can often help to cement an affectionate, lasting relationship between the two, according to Judy Dunn.
Siblings who are not close when young seldom become so in their adult life; what happens in the early years is important in determining how the relationship develops. But even between children who have got on fairly harmoniously when small, the younger child content to follow the older one's lead, tensions can erupt as the younger one nears adolescence and becomes intent on forging a separate identity.
Parents can make a difference here, says Tim Kahn, by avoiding comparisons between the children and avoiding labels - "the artistic one", "the sensible one", "the lazy one" - which often stick for life and restrict each child's need to assume many roles. Instead of protesting that you love your children "all the same", parents do better if they can make each child feel that they are loved uniquely.
And when siblings do fight and scratch and claw? Don't always rush in to adjudicate - even if you do have to separate them so they can cool off a bit. Where possible, step back and encourage them to sort it out for themselves - something that even young children can often do better than we think. As Adele Faber and Elaine Mazlish put it in their book, Siblings Without Rivalry: "When we must step in, it's always with the thought that at the earliest possible moment we want to turn the children back to dealing with each other. We want them to experience themselves as solvers of problems. That's the best preparation we can give them for the rest of their lives."
Parent Network: 0171-485 8535. `Siblings Without Rivalry' by Adele Faber and Elaine Mazlish is published by Avon Books; `Sister and Brothers' by Judy Dunn is published by Fontana.
`I want her to suffer and die slowly,' said Tilly
Aphra, 12, and Tilly, 10, have never got on particularly well with one another. Aphra was not pleased when her sister was born, and used to hit her.
But in the past few years, according to their mother, Doro Marden, their bickering and arguments have grown worse - "perhaps because they are at an age when they are more competitive with one another".
Doro, who is a co-ordinator for Parent-Link, a course on parenting skills run by Parent Network, says she endures the "general squabble level" better than her husband, Leslie, who is more easily annoyed. "As one of four children myself, I'm fairly used to it."
About two months ago, hostility between the two sisters erupted into a fight. Tilly had a friend to play one evening whose parents were having a quiet drink with Doro and Leslie, when suddenly the house was filled with furious screams.
Going to investigate, Doro found her elder daughter incensed because the younger girls would not let her have the sitting room to herself. There had been much scratching, shoving and kicking, and much hurling of insults as well as toys, jigsaws etc. Unable to calm them so that they might try to negotiate a solution for themselves, Doro removed Tilly to vent her feelings upstairs.
"I hate her, I want to kill her, I want her to suffer and die slowly, I want to chop her up in little pieces," she said.
"The difficult thing was not to get furious myself," says Doro. "I was doing deep-breathing and trying hard not to get too involved."
Tilly poured out all her resentment, her feelings that everybody laughed at her because she was the youngest, that no one took her seriously. "Once I'd acknowledged that that was how she was feeling, she did calm down," says Doro.
Aphra, who had meanwhile been talking to her father, came upstairs with a peace overture - not immediately accepted by her sister, who was allowed to eat her supper alone before making it up.
"But this huge fight, which could have made things worse, seems to have made things better," says Doro. "They still argue, but they are much more physically affectionate than they were. I sometimes discover them curled up in bed together reading - which certainly never happened before."
How Cerys bashed the doll, not the baby
Jan Stanton's eldest daughter, Rhiannon, was an angry little girl who was intensely jealous of her baby sister. Rhiannon was 19 months old when Cerys was born. Her reaction on seeing the new baby was to point first to her and then to the door.
The situation went from bad to worse. "She hit her, she kicked her, she threw things at her," says Jan. "It was like living in a battle zone, and I had to put up a stairgate to separate them from one another. I found it very upsetting - and it didn't help when other mothers told me their children weren't jealous of their siblings."
When Cerys was eight months old, Jan started Parent-Link classes, which she had seen advertised at the local play group. "Rhiannon's jealousy was beginning to ease off, but she was still very angry towards the world. If ever there was a fight at playgroup or at someone's house, she would be in the middle of it."
Jan learnt gradually to accept her daughter's anger, rather than always trying to divert and distract her. "I would say to her, `I can see that you are very angry.' I'd leave her on her own for a little while until she was calmer."
Jan also started having balloon fights and pillow fights with her daughter, to give her an outlet for aggressive feelings. "It began to work quite quickly. Rhiannon would have an outburst and be able to deal with it better. She began to have fewer tantrums, and to get over them more quickly."
There were more jealousy problems later, when Cerys was three and Joel was born. But this time Jan was better prepared.
"Cerys didn't try to hurt Joel herself, but she got her teddy, and said, `Teddy says he wants to hit this baby.' Before I went to Parent-Link, my instinct would have been to say, `Isn't teddy silly'. But instead I said, `I understand how teddy feels.' We bought Cerys a big doll, and teddy was allowed to hit the doll.
"For about six weeks that doll really got the works and it was quite hard to watch. Then Cerys broke down one day, and told me that she didn't like the baby, either. She released it all, and after that it quickly became much easier."
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