I can vaguely remember a sort of practice amongst the landed English gentry of old, and I'm hoping someone can correct or confirm the details.
I believe the eldest son is traditionally groomed to inherit from his father.
I believe the second son is supposed to choose a profession, something like law or medicine.
I believe the third son is supposed to go into service, either the military or the church.
How far wide of the mark am I?
AJ