Dubcan Hunter makes the case for birthright citizenship
And we're not being mean. We're just saying it takes more than walking across the border to become an American citizen. It's what's in our souls.
So what is it that makes up someone's soul? I would propose that it's a person's attitude toward life, their loves and loyalties, the way of being in the world that they have absorbed and cultivated. All of these are a product, to a significant degree, of the environment in which one is raised. So if that environment is the US, a person would have the US in their soul -- regardless of the citizenship status of their parents.
So clearly Hunter must mean something different by "in our souls," if he thinks a soul-based criterion creates an argument against birthright citizenship. The full context of Hunter's remarks doesn't give much more clue to the soul theory, since most of his argument against birthright citizenship focuses on the costs to government of providing for additional people. But he seems to be implying a quasi-biological notion of soul content. If your parents are, say, Mexicans, and they did not go through the soul-conversion process of becoming citizens, then you inherit from them a Mexican soul, and therefore aren't truly a member of the US unless you too go through the same adult conversion process as someone born and raised in Mexico would.