[Muromec]

Unconditional jus soli is rare, but a lot of countries have a good approximation of that for a practical reason -- to not have the administrative burden of dealing with people who already live there, participate in the society, pay taxes and all that, but don't get the right papers.

[graemep]

It varies a lot. It does happen that people are refused citizen ship of, even expelled from, the country they were born and grew up in many countries. It is not common, but it does happen.