The rise and fall of a family, the rise and fall of a dynasty, and the peace of the world.
A cause leads to a result, good causes good results, evil causes bad results, cause and effect repays each other, and reincarnation is endless.
This is often the case. The previous generation's causes have left the next generation to bear the consequences. However, who can say for sure? Maybe they have been awake at night, maybe they have cried at night, but that is another story.