How we change what others think, feel, believe and do
Enmity of kinsmen
Next: Rivalry of kinsmen
Two relatives hate one another (and act accordingly).
A sadly common theme through many societies is the family feud, where two people not only do not get on with one another but their dislike blossoms into full hatred and all that that entails.
The problem with family is that love them or hate them, you can't escape them. Just because you do not agree with what they may say or do, they do not stop being family. This can make things worse, as you share the family name and when a relative does something you consider bad it is, in some respects, as if you have done that thing in some way. This can also leak beyond the walls of the family home, for example, where a criminal's family may suffer socially, all being branded as somehow criminal. They might thus be forgiven for hating the black sheep of the family.
Family hatred can also have deep, psychoanalytic roots, for example where the Oedipus Complex is not navigated successfully, and enmity between parents and and children becomes an ingrained pattern. Likewise early sibling rivalry for parental attention can morph into long-term grudges.
Infanticide is still alive today, for example in cultures where having a baby girl is less desirable than having a boy, or where teenage mothers are just unable to cope.
There is much in real-life about family hatred that translates into stories. Soap operas, for example, often rotate around family friction. Such disputes can also lead to grander adventures, for example where a child achieves great things in order to 'show' parents or relatives what he or she is made of.
'Enmity of kinsmen' is the 13th of Georges Polti's 36 Dramatic Situations.