Gurps Traveller Rim of Fire is one of the best setting books written. It's got a good bit on how the Imperium operates in that vision.

Short answer: a clone counts as a younger sibling of the genetic donor. Longer answer: Generally a clone (commonly called a true-child) in most cases is treated like a younger sibling for the purposes of inheritance. Free clones, like Seldarian, are those independent to develop their own personaliti...