Plenty of countries do very well without shared ethnic seeds, whatever that means, including the wealthiest country in the world.
Edit: Thanks for explaining what you meant, below. That makes sense.
I explained that they're different because they're comprised of different people with different histories.
This might be obvious to you but in my experience a lot of people assume that the inhabitants of the Hispaniola came from the same seed, as in they were the same group of people who later split when that was not the case. One country was seeded by the Spanish and the other one by the French.
My comment was not meant to be a thorough analysis on their respective economies.