Continuities in sibling relationships: patterns of aggression and friendliness.

Thirteen girls and 12 boys who had been observed at home as 2- to 3-year-olds with their mothers and infant siblings were interviewed as 6-year-olds about their relationship with their siblings; their mothers also were interviewed. The marked individual differences found among the 2- to 3-year-olds in comments about their siblings were correlated with differences in the children's comments about their siblings 3-4 years later, and the differences in their behaviour towards their siblings as 2- to 3-year-olds were correlated with differences in their mothers' accounts of the sibling relationship at the 6-year visits.