I recall a previous thread where someone said that not just Lancaster and Cornwall, but it was mentioned a number of these titles are attached to the certain lands, and as a result the title, not the person, owns the lands. The current title holder cannot sell those lands, but simply owns them in trust to hand down to the next title holder?
Was it about fee tail?
I think md-2000 is talking about if a person owns the Mangrove Estate, they are now Earl of Squigglyspooch. This used to be a thing but at least in the UK, not for a few centuries.
A little searching gives a link to Frederic Maitland’s essay on the Domesday Book in which he writes that
As with the estates of the king, so with the estates of the earls, we find it impossible to distinguish between private property and official property. Certain manors are regarded as ‘manors of the shire’ (mansiones de comitatu); certain vills are ‘comital vills,’ they belong to ‘the consulate.’
But, yeah, that was a few years ago.
Up until the oughts you could’ve been born the Dame or Lord of Sark
Until the second half of the 2000s Sark was considered the last feudal state in Europe.[47] Together with the other Channel Islands, it is the last remnant of the former Duchy of Normandy still belonging to the Crown. Sark belongs to the Crown in its own right and has an independent relationship with the Crown through the Lieutenant Governor in Guernsey.[48] Formally, the Seigneur holds it as a fief from the Crown, reenfeoffing the landowners on the island with their respective parcels. The political consequences of this construction were abolished in recent years, particularly in the reform of the legislative body, Chief Pleas, which took place in 2008.
Yes, that seems to be what I was remembering.
Thanks
Or, I suppose, by conquest of new lands. Not sure how often this was the driving force behind medieval wars but it wouldn’t at all surprise me if it was.
Very much so, albeit often dressed up with claims to legitimacy of succession (William the Conqueror - Saxon England was seriously wealthy, the Hundred Years’ War) or divine sanction (you could say that goes back to the Milvian Bridge).
Come to think of it, it was so much the norm that it was considered worth remarking that the Habsburgs acquired most of their lands and titles by marriage.
This of course is the origin of the duchy of Lancaster and all the other royal and aristocratic holdings in the UK, being ultimately traced back to William the Conk 
“We live in a bloody swamp! We need all the land we can get!”
No chance, English pig-dogs. I fart in your general direction.
An example for what the OP is looking for is the Ceremonial Official to Confucius. This is a government office in Taiwan (a republic), which, following a Chinese tradition that goes back more than two thousand years, is always held by a direct male-line descendant of Confusius. It’s currently unremunerated but was remunerated until 2008.