How strong is the sibling bond? The relationship with your brother or sister is probably the longest bond you will have in your lifetime. Research shows sibling interactions have a vital role in teaching kids valuable social and life skills, and in shaping personality and behaviour. But siblings also sometimes get stuck into each other. Parents may see this rivalry as part and parcel of growing pains, however there is a growing body of research showing early sibling aggression is linked with serious ongoing learning and mental health problems. Are such disputes unavoidable, and do tensions always persist into adulthood? This week Insight asks: When is competition and conflict between siblings a good thing, and how can favouritism affect this. We also look at how this plays out in families from cultures with a hierarchical or gender preference. Have you ever experienced sibling rivalry?