Sibling rivalry often continues throughout childhood and can be very frustrating and stressful to parents. Adolescents fight for the same reasons younger children fight, but they are better equipped to physically, intellectually and emotionally hurt and be intellectually and emotionally hurt by each other. Physical and emotional changes cause pressures in the teenage years, as do changing relationships with parents and friends. Fighting with siblings as a way to get parental attention may increase in adolescence. One study found that the age group 10 to 15 reported the highest level of competition between siblings. Sibling rivalry can continue into adulthood, and sibling relationships can change dramatically over the years. Events, such as a parent’s illness, may bring siblings closer together, whereas marriage may drive them apart, particularly if the in-law relationship is strained. Approximately one-third of adults describe their relationship with siblings as rivalrous or distant.