Sibling rivalry can be a year-round tradition for some families. University of Missouri researchers followed more nearly 150 pairs of siblings for a year and found the conflict fell into two overall categories:
1. Conflicts about shared resources and responsibilities which focused on equality and fairness, like whose turn it was to empty the dishwasher or use the computer or ride in the front seat of the car. These siblings were more likely to become depressed.
2. Meanwhile, those who argued over privacy and personal space, such as borrowing clothes without asking or entering a room without permission, were more likely to be anxious and have low self-esteem. The most vulnerable for this twist were younger siblings.
The researchers say the way preteens and teens react to the conflict with siblings to the has to do with what they perceive is at stake. You'll find details about the study in the journal Child Development.