Abnormal, deviant, disruptive (such as an incestuous relationship, fighting between or killing of close kin).
Marriage or enmity (to the point of physical injury or death) between parents and their children, siblings, or uncles/aunts and nieces/nephews is considered sumbang. To a lesser degree such a relationship between first cousins. A breach of the rules governing these relationships is believed to have bad effects on the whole community as it may result in supernatural retribution such as a drought or flood. People involved in a breach of such a relationship have to be judged and pay fines in order to make things right again.
If parents and children or siblings kill each other they are deviant.
If siblings become husband and wife they are involved in an incestuous relationship; they have to be killed.