The definitive case on this issue is US v. Wong Kim Ark, which makes it very clear that a person born in the United States to non-citizen parents is a natural born citizen. Minor v. Happerstett is about women’s suffrage, not natural born citizenship, and the quote birthers rely on only suggests there might be a question about the natural born citizenship of the children of noncitizens. That issue was conclusively settled in Wong Kim Ark.