Read more on this subject: Philosophy: Libertarianism
News Story Source: https://www.zerohedge.com, by Murray Rothbard
The Anglo-American model, in which every baby born in the country's land area automatically becomes a citizen, clearly invites welfare immigration by expectant parents. In the U.S., for example, a current problem is illegal immigrants whose babies, if born on American soil, automatically become citizens and therefore entitle themselves and their parents to permanent welfare payments and free medical care.
Clearly the French system, in which one has to be born to a citizen to become an automatic citizen, is far closer to the idea of a nation-by-consent.