Child's play? Not at all, says Dr David Campbell, consultant clinical psychologist, who explains that children as young as seven are busy ... their identity outside the family.

'They are developing relationships that give them ... about what kind of person they are - pretty, sporty, and so on. It's a very important time for them.

Psychological theories indicate that women are more ... to find their identity through relationships than boys, who define themselves more through activities,' he adds.

'At first, rejections are ... painful for girls, so they can seem much more important than they really are.'

He points out that the oldest child may feel more threatened by relationships that ... wrong.

'If they lose a girlfriend at school, it reverberates with all their past experiences of ... to siblings.'