The main trait of my story originates from a village in what's now the Belgian city of Tongeren, around 1000 BC in our timeline. Anyone born there after that trait arrived will have the trait, as will their children, recursively, regardless of where they are born. The trait doesn't have a single Patient Zero like Mitochondrial Eve or comparable people, but rather that everyone born in that village after the date the trait started appearing has the trait.
In the backstory, the Belgian empire that sprung from this city gradually takes control of Earth, with Europe being fully theirs in 500 BC, The Middle East around 1 AD, Africa and the rest of Asia at 500 AD, the Americas at around 1000 AD and the remaining landmasses of Earth at around 1200 AD, with tech being roughly at our level at around 1400 AD. These are rough estimates that aren't fully established yet, but the idea is that in 2050 AD, the Belgian Empire has developed interstellar travel, contacted and befriended other aliens and is a relatively new player at the galactic table.
Judging by the above estimates, how likely would it be for humans WITHOUT this trait to exist and be adults in 2050 AD?
information requested in comments:
the trait always gets passed to the descendants and is always active. The trait doesn't directly increase survival through resistances or similar, but it does indirectly increase survival by providing the affected party with additional inherited knowledge, increased mental acuity and being able to use senses remotely. There are ways to lose personal access to the trait, but it doesn't affect how the trait gets passed on.
the trait is not genetic in nature! I see many people assume it's genetics and thus obeys the normal Survival of the Fittest criteria where it only gets passed on if the trait is beneficial for survival. The trait is not dependent on the genes of either the mother or the father and will always be passed on to any children of the person affected.
The empire achieved global dominance through a mix of diplomacy and military strength. Where possible, countries were annexed through treaties, royal marriages and other nonviolent means. when the empire is attacked, the offending nation is conquered, although this is mostly happened in the pre-BC days, when the Romans invaded from Italy and were conquered.