Fourth, one must determine the goal of the questioned and/or questionable behavior: while rivalry is motivated entirely or primarily by aspects of a childs self-interest in which the interests of others, including the childs rival, do not play a role, in scenarios featuring abuse, the perpetrators ultimate interests tend to include domination, humiliation, or at least embarrassment of the victim. Animals
Sibling rivalry is common among various animal species, in the form of competition for food and parental attention. An extreme type of sibling rivalry occurs when young animals kill their siblings. For example, a black eagle mother lays two eggs, and the first-hatched chick pecks the younger one to death within the first few days. In the blue-footed booby, there is always the emergence of a brood hierarchy. The dominant chick will attack the subordinate one in times of food scarcity, often pecking it repeatedly or driving it from the nest. Among spotted hyenas, sibling competition begins as soon as the second cub is born, and 25% of cubs are killed by their siblings.Sibling relationships in animals are not always competitive. For example, among wolves, older siblings help to feed and guard the young. Famous instances
In religion
The Book of Genesis in the Bible contains several examples of sibling rivalry: the story of Cain and Abel tells of one brothers jealousy after God appears to favour his sibling, and the jealousy ultimately leads to murder.
Brothers or sisters in a similar line of work may display professional rivalry. In serious drama, conflict between siblings can be fatal, as shown in crime dramas involving such rivalries. Real life
Occasionally real life instances of sibling rivalry are publicized in the mass media. Siblings who play the same sport will often be compared with each other; for example, American football players Peyton and Eli Manning, or tennis players Venus and Serena Williams. Musicians Liam and Noel Gallagher of Oasis have a turbulent relationship, similar to that of Ray and Dave Davies of The Kinks. Politicians Ed and David Miliband are likewise portrayed as having a strained relationship, after Ed narrowly defeated David in the final round of the 2010 Labour Party leadership election (UK).Actresses Olivia de Havilland and Joan Fontaine had an uneasy relationship from childhood and in 1975 the sisters stopped speaking to each other completely. The incredibly popular singing Andrews Sisters maintained professional harmony in show business for more than 30 years, but clashed famously in their personal lives (after LaVernes death in 1967, Patty and Maxene stopped speaking in 1975 and never looked back). The rivalry between singers Lata Mangeshkar and Asha Bhosle is often talked about in the Indian media, in spite of their insistence that these are just tales. Twin sisters and advice columnists Ann Landers and Abigail Van Buren had a relationship that was alternately very close and publicly antagonistic.