I would say you only have (limited) influence over the nation you are born into... so, you should somewhat naturally favor that nation's well-being over others.

I would say you only have (limited) influence over the nation you are born into... so, you should somewhat naturally favor that nation's well-being over others. You can only influence the acts/actions of other nations as strings attached to trade/treaty. And can only assume those that you trade with will be making the same emphasis, which is their own nation's well-being.