There is a word in Japanese "tawake", which means "stupid"　or "foolish", but the literal translation is "splitting the rice field".

Every time you split your fortune, it becomes far less powerful. As generations pass, your "fortune" splits and splits until you've got a bunch of insignificant sums among your descendants.

This is why the powerful families choose ONE child who will receive the inheritance, while the rest must make their own way. The common practice is for the firstborn to take the inheritance, but the best practice is to wait and see how each of your children deal with money before deciding.